I have one child and I can't have anymore. I hasn't decided if my family was complete before the decision was taken from me.
If a close friend got pregnant with their second I'd be upset. I'd also be happy for them but I would resent that I couldn't have a second pregnancy. YANBU. But yes, you do need to get over it and be happy for them. Easier said than done and completely understandable if you struggle to do so. But don't let it ruin your friendships or drag you down.
Just wanted to add - you need to grieve for the baby you can't have. If you don't then you'll find it hard maintaining a relationship with these women. It's sad you can't join these women in their pregnancies and you are entitled to feel that way about it
I have 2 children, and had decided that I definitely didn't want any more. Then I discovered I have the BRCA1 gene mutation and the month I saw my consultant about having hysterectomy and BSO, one friend gave birth and another found out she was pregnant. This shook me, and as I said, I'd already decided I didn't want any more, so you are not being unreasonable for feeling like that.
I did get passed it, and have since had my hysterectomy, though my situation was different to yours