I also lost my daughter in March. She was born fighting at 25 weeks, but we lost her the next day. I had to have a c-section so I was out of it the night after she was born and didn't get to see her until the next morning. I wish with all my heart I could go back to that day because I would have demanded to stay in the NICU the entire night, if they would have let me. I only saw her thriving for a few minutes that morning, the next time I saw her we were saying goodbye.
I struggled a lot in the beginning with seeing pregnant women. I had to have my postpartum appointment with my MFM, whose office was on the OBGYN floor of the hospital. So three weeks after losing her, there we were, surrounded by happy blissful pregnant women and even harder to see- new mommies. My body ached when I heard the babies cry, it still does actually.
It's been 7 months for me, so it is a little easier. I work in retail so I see pregnant women all of the time. They don't bother me so much.. it's the new moms cuddling their little baby girls that pull at my heart. I want to tell them "I had a baby once".. but I bit my tongue and carry on.
As for advice, I would be honest with everyone (especially if it's family) and let them know how you're feeling. Share that you are very happy for them, but that you just don't feel ready to be around them. You may get a few insensitive comments from those who expect you to be over it, but don't let it bother you. You suffered a loss that not many have and you have every right to grieve however and for as long as you need.
Mommy to Gracie- born at 25 weeks 03/15/11, 11 inches, 1.1lbs, and absolutely beautiful. Became my sweet angel the next day.