Shortly after my gf had her baby, I was fretting to a friend about the relationship. He said "Your old relationship is over. You can't have that relationship any more because she's a different person, literally, chemically. But you can try to build a new one." I found that thought sad but also very helpful. Expectations based on how things had been before were of no use to me, so I was better off just letting them go and focusing on supporting her and loving her right here and now.
If I were you I'd tell her I loved her, vow to give her all the space she needs for as long as she needs it, let her know that I very much hope we'll be intimate again some day but that I'm not just hanging around for that possibility but rather because I value the bonds we've built and the friendship and the family, ask that we not make any big decisions now while things are still a moving target (since, after all, the baby wil change things even more than the pregnancy), and affirm that I'll go at her pace and be only as involved as she's comfortable with. Let her know that this is not some hardship she's putting on you, but your choice freely made out of caring. Then work really hard at meaning all of those things.
The major players. Me, 30ish bi female. Gia, girlfriend of 4+ years. Clay, boyfriend/dom. Davis, ex/friend/"it's complicated." Eddie, roommate & fwb.
The supporting cast. Eric, Gia's husband. Bee, Gia and Eric's toddler. Dexter, Gia's lover. Helen, Eric's lover. Izzy and Nikki, Clay's partners. Liam, Eddie's husband.