if your mom is anything like my mom then i'm pretty sure the reason it would kill her is the thought of you not having a wife and kids one day... the idea that her son is gonna be judged and discriminated against for who he sleeps with and not for who he is.. and the whole promiscuity and aids problem in the gay community
From my own experience I am willing to bet that this is the reason why your mom is sending mixed signals. I think most good parents look at their children and besides hoping that they do well in life, they want to see them living that "married" life. Complete with a nice house and kids. Granted, you can still have that only it will not be as she envisioned it.

