It's going to really be hard for you to do this, but maybe the best thing you can do right now is to tell here you'll be there for her when she needs you and take a step back.....she's a grown up now, she has to make her own way in life, even if she makes what seem to us to be terrible choices. Chances are she won't listen anyway.....
Sounds like a classic case of "he'll love me again once the baby gets here"........