I don’t know how to feel

So me and my boyfriend have been together for about 4 months now, before that we started for about 8 months my freshman/sophomore year. 3 years later we got back together and I’m very happy I Love him and I’m happy he’s back in my life . When he were broken up I still had feelings for him and of course he started dating other people and so did I. He had about 2 serious girlfriends but I never really had a relationship that I actually enjoyed after him. Anyways that’s just little details. So yes we got back together and the other day I looked through his phone and he still has pictures of him and his exes and screenshots of the girls. I don’t know why he still has them. I feel a bit insecure, I don’t know why. I also feel sad and upset but at the same I feel that I shouldn’t care because he is with me now. It’s very confusing I don’t know how to react or feel about the situation. Anything will help I just need advice from

Someone who understands.