I don’t know what to do

My boyfriend and I have been together for at least a year now. But a couple months into our relationship, I found out he got his ex pregnant. (We weren’t together when she got pregnant and she told him 3 months before her due date) Despite that, I chose to stay with him because it was so hard for me to open up to a person and I finally did w him. So I wasn’t ready to lose him already. For some reason it all finally came crashing down a couple days ago that he has a kid with someone else. Idk if I’m being dramatic but it just makes me upset knowing that I’m not gonna be the first to experience that w him or even have his first kid because he already has one.And I feel like when I do tell my parents about the baby, it’s gonna be a disaster especially since he has a kid at 17. I overthink so much to the point where I believe that he’s going end up leaving me to be w her and it kills me. I want to tell my bf about this but I don’t want him to know it’s bothering me so much.