You are definitely the more stable of the two of you right now, and you are giving your D the better environment right now. I would definitely lay off the discussion about custody and such, especially over text messages: that kind of stuff could have a way of coming back to bite you if your M ever does go south.
Have you spoken to a L yet? Many Ls will give a free consult to help ascertain what your rights are. I would definitely talk to one and find out what options you have.
Me40 WAW37 M18 T20 S18,14 D13 EA Bomb 6/08 Sep 11/20/08 Ret 08/09 Sep/Filed 11/09