My relationship and trust issues

So me and my boyfriend just recently moved in with each other. When we first meet he would go to a jail place and see somebody I use to always ask was it a girl and he would never answer. So we would hang out and one day we got into a big argument and I guess she got out of jail he went to see her and had sex with her a couple days after we got into it , I just found out like 2 or 3 days ago. I know we wasn't going out yet but I like him and I trust everything he said to me. Then I have to deal with the fact that he has to see his babymama a lot cause he takes there daughter to and from school. He said he didn't have her as a friend on Facebook and come to find out he do. I've never meet his kids and really dont know to much about them I just know its girls. Idk what to do and I didn't want anything to start off like this. What should I do any advice?