If it was YOUR "baby mama" I'd say try. Since this is your boyfriend's ex-girlfriend...don't bother. In her eyes you probably stole her away (even if it was over) and you are the enemy. Unless/until you become a permanent fixture in his life (5+ years in the relationship, marriage, etc), don't count on her softening this attitude! I have baby mama drama from my husbands ex and it's been over four years. I'm not sure it will ever change. I'm just waiting till the kids are old enough to make their own decisions so we no longer have to deal with her directly. She has a new baby, you have her "man" or whatever he is, and she is struggling right now. You should stay away from her until all the dust clears because it hurts her too much for you to be around. You have no reason or business to be around. There's nothing you can do to force her to like you. All you can do is show respect for her and her child but that probably won't be enough. Try to avoid her as much as possible. She probably still needs time to get over him. Were they already broken up when you came along?