Hi B.,
It is nice to have me someone who you have such deep feelings for especially from your own country, but HONEY, YOUR SON should be the MOST IMPORTANT THING IN YOUR LIFE RIGHT NOW!! It is not about you anymore!! This is one my biggest pet peeve with single parents, partly because I have seen the repercussions from it in children and partly because you have plenty of time to get into another relationship!! You only have your son for 10 to 15 years (they stop listening to you around then) and you have got plenty of time to find another "significant other"!! I don't mean to sound so harsh, but I have a real problem with this.
Put your son first, he has already had to suffer the effects of divorce, concentrate on him. I think you allowing him to meet your friend and do activities together is fine, but slow down honey!! Six months is no time to really know someone, give it more time. You are a package deal and whomever you get involved with must understand that and that your son NEEDS TO BE #1 at this time especially at his young age.
If this is also the first guy since your marriage, go very slow! Rebound relationship (like someone else said) aren't usually successful. Take your time, you have so much time .....also, why do you just want to "live together"? I don't want to get moralistic on you, but what kind of example and impression are you making on him?
Consult a lawyer with regards to the "custody issue". This will definitely NOT make your EX happy and he will take you back to court over it in a NY minute! Texas law does NOT look kindly on folks "livin' together" with regards to ex-spouses, it just shouts "temporary situation" when you are trying hard to cultivate consistency and steadiness in your son's life.
Just remember, guys come and go, but children are forever!!
Good Luck!
G. B.