Need Advice

So I’m dating this guy and I really like him. It’s going really well between us, but when we were talking about past relationships he happened to have sexual history with two girls I am very familiar with. We all grew up in the same church and when he said that I immediately felt awkward and was like wow! I asked him if they still have any type of conversations and he said only with one of them. I know it’s the past, and I don’t have an issue with that, but I don’t want it to be an issue in the future. I didn’t think I was going to be so bothered by it until me and him started kissing and all that went through my head was those girls and him. I know I need to let it go, because the past is the past and I definitely see a future with him. Any advice on how to move past this?