How to Deal with Boyfriends Ex Wife?

Start a log. Dates, times, and very objective reports of behaviors: '9/11/10 at 2pm: Ms. X arrived at house in tears.' Include specific quotes from her, keep a record of text messages, emails, etc. If she's showing up at your house or calling you, there's nothing to stop you from making a recording- you can do whatever you want in your own house. On your own part, try your very very best to not feed into any of her behaviors.
It's truly sad when a person has a mental illness, but when a child is an innocent bystander that is even harder. It really is up to your husband more than you to stand up here- you are the stepmother. As far as the girl calling you mommy- I would recommend against that at this point, but suggest another special name that would validate your unique relationship. It could be anything, from Sugar Pie to Wolverine for heaven's sake, the point is the girl wants to feel close to you and celebrate your relationship. As the big girl, help her do that in a way that doesn't threaten her mother and cause her more issues.

Unfortunately, since she is no relation to you, has no impact on your life, etc. then I don't know if you can do anything legally. The DAD can, but until you are married, you can't.

You might try calling Family Services on her anonymously from a pay phone and let them know she is abusive (verbally) and neglectful of her daughter. They should have to investigate, and in the meantime the dad should get custody. Ask an attorney. If she is bipolar, she needs to be on meds and stop partying, but you cannot control her. You can only control your situation, so do what you can.

All the best.

I haven't read all the responses but the one thing I do want to suggest is get the child into a child therapist. The faster you can do that the better. I know it sounds drastic but it can and will help your bf. Make sure when you pick one that he/she has court experience. You can talk to s/he about this and once they have had a few sessions with the child go back in and talk about if the therapist thinks it is in the best interest of the child to live with you and your bf.
Make sure you let the therapist see all that you have documented about this whole situation.
Since you are writing stuff down make sure you are also documenting the stuff you are reading on her facebook. It is real easy to get screen shots of the stuff she is posting for all to see. Also if you know someone you trust who lives by her see if they will take pictures of any and all vehicles that are going in and out of her house. If they can to also make sure to get pictures of the owners of said vehicles. This way you have the proof of various men being in and out of the house. This will show that the child is being exposed to these men and possibly dangerous men to the child.
Also check with the lawyer and see what the laws in your state are about recording conversations. This way on the times she shows up clearly upset or the times she drops off the child for whatever reason you can record exactly what is said. Like I said check the laws before you do this. Some states are really touchy about that.

You are in a tough situation. Her mother will not be happy (can't say as I blame her) but it doesn't seem like she is happy anyway. You have to do what is best for the child even if her mother isn't. Telling her it is ok to call you mommy is sure to confuse her because her mother will demand that she doesn't. Are you and her father engaged with the intent to get married very soon (like in the next few months)? If so maybe you could tell her that you would be honored to be her "mommy" but since you aren't you don't want to upset her mom and maybe "Mama Steph" would be a reasonable option. If there is no immediate plans for marriage it isn't fair to allow either because that would be hard on her if you and her dad split up later.

Sounds like your boyfriend may need to go back to court because this is not good for his daughter. I find it incredibly disturbing that people do this to their children. I realize she isn't being the type of mom that she should but be cautious of being so bitter sounding...kids do pick up on that.

Updated

You are in a tough situation. Her mother will not be happy (can't say as I blame her) but it doesn't seem like she is happy anyway. You have to do what is best for the child even if her mother isn't. Telling her it is ok to call you mommy is sure to confuse her because her mother will demand that she doesn't. Are you and her father engaged with the intent to get married very soon (like in the next few months)? If so maybe you could tell her that you would be honored to be her "mommy" but since you aren't you don't want to upset her mom and maybe "Mama Steph" would be a reasonable option. If there is no immediate plans for marriage it isn't fair to allow either because that would be hard on her if you and her dad split up later.

Sounds like your boyfriend may need to go back to court because this is not good for his daughter. I find it incredibly disturbing that people do this to their children. I realize she isn't being the type of mom that she should but be cautious of being so bitter sounding...kids do pick up on that.

What a tough situation. I think at 4 years old, she's old enough to understand when you tell her she can call you mommy, but not in front of her mother. I think she will get it.

Thank you for being some stability in this poor little girl's life.

p.s. There is a problem with that. If she calls you mommy, and then you and her dad break up...

I know exactly how this is for u i am 19 n i am a mother to one of my own the my fiancee has 3 boys fr his ex-wife... we are currently trying for full physical n legal custody...his ex-wife disappears n leaves the children with me n there father all the time...she is currently about 4 n 1/2 months pregnant by the guy she cheated on my fiancee with when they were married...my one child is from my fiancee...he is currently 3weeks old...my fiancee's ex-wife parties all the time annd yes even while she is pregnant...me and her made an agreement before i had my son where i kept her 3boys for 4days so that when i went into labor and went to the hospital she would watch "her children" so that my fiancee could be there with me...because she will not keep her kids one minute more than she is legally obligated to unless we "make up the time". and when i went into labor an was at the hospital she flipped out and said that she was taking note on how my fiancee didnt get his boys fr her when the court papers say he was supose to n i said what are you talking about we made an agreement to keep them and i did so that you would keep them while i had my son so that my fiancee could be there with me for the birth of "our" son and shes all like what are you talking about we didnt make an agreement i didnt sign anything...she currently gets here children for 5 n 1/2 hrs a day fr 4pm till 9:30 pm and 75% of the time she calls or texted me saying she is either not gonna be home to get her kids at 4pm or can we pick the up an hr or two early because she has stuff she as to get done like change the oil in her car or meet with her lawyer( and let me remind u these things are things she waits untill after regular busyness hrs to get done) she trys everything she can to make it difficult to switch the kids off between us and her...she tells her kids that if they call me mommy the will knock the hell outta them...she breaks up n gets with her current boyfriend all the time 1/2 the week there together the other 1/2 there not...her childrens ages r 20 months 3yrs n 6yrs old...the children cry the whole time were dropping them off and the older two who understand more and are able to talk begg us not to make them go and stay...and much more she went an filled for custody saying she wants them for one week and then for us to keep them one week and my fiancee was just like you cant even get them the 5 1/2 hrs a days ur suppose to now how r u gonna do a full week... she leaves them with babysitter the majority of the time she is suppose to have them....and the only reason she went and filled custody is bc the last time we went to court the courts considered there custody 50/50 but wit a wrighten out schedule we have to go by and the state started taking her food stamps (which i think she use to sell for "shopping money" ) her section 8 she got on the boys which if you dont know what that is its a certain amount of money she is giving by the government to make rent she lost her TANF and the medicaid she revived on the boys the days she found out she lost all that she made arrangements to meet with her lawyer the very next day to file for custody bc shes a welfare mom and will not get a job when she isnt pregnant and will not go to college to try and make a better life for her children... her children randomly say they hate her and dont want to ever see her again because she is mean to them and she hurts them we did call social services so they can make 100% sure she isnt abusing the children physically... an we have been to court for custody before and she plays the innocent role of a Sunday school teacher and none of our evidence is ever good enough they always believe her instead... and we dont no what to do we have court again in two weeks and are worried the custody is going to change but only for the worst....we keep doucument of all text and phone calls n times she drops them off so she can go to the mall an shop or go party or because she says she simply cant handle it...the weekend after i had my son he was sick we were in the hospital for several days after my son was born an i had no experience with new borns espcially sick ones and the court papers said she was suppose to keep them that weekend and she said she couldnt because from where she is pregnant she cant take her depression meds so she couldnt handle her children that weekend she said all of this while sittin inthe walmart parking lot putting on make up with some new guy in her front seat...and she disappeared for a week leaving her chidren with me in that situation because my fiancee works all weekend goes in at 6 am n doesnt get home till almost 5 pm working at a factory on the weekend shift... we have so much stuff on her but none of it is ever good enough in court and dont know what to do if you figure anything out let me know and if i figure anything out that could help you ill let you know!!!!

Really, what can you "do"? The mother is clearly unstable. You are the father's girlfriend. Are you guys living together? I would imagine that could be confusing for his daughter, not to mention your two kids. Not sure from your post, but I'm assuming you are or else his time with her would be "his" time with her...I know how she'll "take it" if this kid calls you "mommy" and your her dad's girlfriend--she will freak out--bi-polar or not. I probably would too.
Overall, if you're not married to this man, I feel it's a bad idea to let her call you "mommy" b/c you're not, and your not her stepmother either. Maybe Mama S.? Miss S.?
On another note, do you realize the anger that's coming across in your post toward this woman? You criticize her for getting pregnant the "first night he met her". Well...he was there too right? You refer to her as the "mother" (in quotes) like she's not a mother at all.
Don't sink to the level of a crazy. Always take the high road and treat the little girl with love and kindness.

Documenting everything is good advice. Is there any way to have the court request psychological and/or bonding evaluations (they will probably want to do them on both parents if they do one)? I am pretty familiar with child welfare type cases but not as familiar with regular custody cases. You could go the route of involving child protective services if you feel she is unstable to the point her children are in danger (especially the little one). But they are also limited by needing evidence to go to court with. If there isn't anything substantial enough for family court it may just increase bad feelings and make things more difficult. Also you may want to wait until you are married to make more waves. If your boyfriend's daughter is really having a hard time or seems upset there is always the option of counseling (for her or as a family). I have family friends that each had previous marriages with children and did couples counseling for a few months before their wedding. It really helped improve the communication and not get hung up on old baggage (they have been together about 20+ years now and are grandparents).