I sound selfish as shit

So at 17 I got pregnant with my high school sweetheart. I sadly ended up miscarrying. Well fast forward me and him broke up! I’m still extremely close to his family but I got married and have 5 kids with my husband now. Well him and his current gf just announced there pregnancy. My baby was a boy and they think they are having a boy! I’m not sure why but it’s completely killing me. I don’t want my ex back by any means but I was destroyed by this miscarriage when it happened. He was fine. Granted we were young but I talk about this baby all the time. I got memorials for this baby. I fully loved our baby with all my heart! He’s fine like he’s always been. His siblings talk about their baby all the time. I’m also worried as hell for my 5 kids they consider my ex’s family their family. They call his siblings there aunt and uncle. Like I know it’s bound to happen and I should of protected the kids but I’m afraid they are gonna be replaced by their biological niece/ nephew. I know I sound so selfish I just need someone to talk too.