From the way you describe her in this post she doesn't seem to care for your needs at all. She has repeatedly hurt you and taken advantage of you. Why are you doing this? It's not your responsibility to take care of someone else's baby, especially not for a partner who doesn't respect you. Have faith that you can build a real life for yourself with a partner who wants YOU. Her disastrous life is not yours to fix. Please get out. Just because she is smiling now doesn't mean that she's going to be smiling after she has the baby. It is very very unlikely that a child will fix her problems or change her feelings and actions towards you. This is much more likely to become increasingly horrible for everyone involved.