Boyfriend and a baby daddy 😑

So right after my ex and I broke up in 2014 I became friends with an old classmate who was in a relationship. I respected my friend relationship but him and his girl friend broke up so a few months later we started being intimate I didn't want a relationship because I still loved my ex. So a year later my ex popped up out the blue and I told my friend I wanted to work things out with my ex and he respected it. 4 months passed of me dealing with my ex things didn't work out and a few weeks later I found out I was pregnant. The first person I told was my friend and since day one he's been by my side. My child's father and I haven't spoken since the night we conceived but he talks to my mom  (which I think is childish). My friend and I decided to make it official even tho I'm 13 weeks pregnant. Though my friend and I have already been sexually active we always talk about having sex but will I be wrong I'm pregnant from someone else? We decided to make it a family thing oh yea he has 2 kids and I have a 6 year old so we will have 4 kids. We laid everything on the table because like I said we were friends first so we still talk like best friends. I get sexually frustrated and I always stop before we begin because I don't wanna feel trifling but it wouldn't be the first time and I'm so comfortable with him. Advice please!!!