D.P.
I had similar issues. For me it lasted 16 weeks. The exact amount of time it took for two other moms I know. I think it was mostly due to utter fatigue. That made me feel like I was in over my head and that I was not able to be a good mom and since I could hardly keep up with housework, I was miserable at the end of the day. I remember begging my husband on several occasions to come home early from work because I needed a break so bad- not just from fatigue but because, like you, I felt like I couldn't do one more load of laundry or dishes or answer one more "why?". I thought I would need to go on antidepressants but decided to wait it out until the 16 week mark. Sure enough, I felt much better all around by that point and I'm still doing well in my 7 month. Hang in there, I think you'll be feeling better soon.
You could need to get on an antidepressant. Talk to your OB and don't brush it off if it continues.
BTW, I'm working on #3 right now. The transition to #2 was not nearly as bad as I feared. Newborns sleep a LOT so the first couple weeks are not so bad. My daughter loved all the attention she got as I tried to overcompensate. She also loved all the TV time while I breastfed.
At the same time, I can honestly say that I rarely wear my hair down anymore and rarely shower daily. Also, god help my husband if he is late coming home from work or if he is having a head-up-his-butt, zoning out day. It's damn hard work (mine are now 4 and 2) but I think without the overdose of hormones we get when we're pregnant, it's doable and enjoyable most of the time. The only time I was sick of my life and wanted a serious break was in my first trimester.
Good luck!!!