So you were dating before your W even moved out. I guess this makes more sense now.
So in the early stages of a relationship and especially after having a child a woman will typically bends over backwards to make her husband/BF happy so he stays in the relationship. This is all part of the Evolutionary Psychology thing I like to talk about on this board. She wants a man around to help with, protect and provide for her and the baby. After years and years of this and the man doesn't reciprocate the resentment starts to build and you get the bomb drop after many years of her needs not being met. The fact that this has happened so quickly leads me to believe either A. you are not being honest with us or B. your girlfriend is not relationship/marriage material or something is not right with her like for an example she is not attracted to you.
So anyhoo what I would do if you want this relationship work is to focus on her needs for at minimum 6 months. If you do this and she is a rational human being she will slowly start to meet your needs too. After 6 months of your efforts she still is not reciprocating you should have a discussion and try to at minimum negotiate a middle ground. If the negotiation is not acceptable to you than you need to live with it or start to plan your exit strategy.
