Advice? Please no harsh comments

I have been with my fiance for 3 years now, and about a couple weeks ago I found out he has two kids... I've been trying to work out it in my head. Like I've planned this whole life with him and now I'm kinda confused. He said he was young and partied that's how his kids came along. He and I have been trying to have a baby for the longest.. And I feel like I can't get pregnant. I've been trying forever and. Now everything. I see kinda triggers this anger and upset. Like idk I have this weird thinking and he's given me. Plenty of chances bc I promised him I wouldn't negative or dramatic and I'd end up being that way. It's hard for me too let go of things. I just need someone to talk to or if someone went through that.