crazy jealous

Let me just start with a disclaimer. I know what I'm doing isn't healthy. I'm here asking for help - not to be judged and ridiculed. 
My husband (married 5 months now) and I went through a period of struggling with infidelity. He didn't physically cheat but was exchanging nude pictures with women and was lying about it. This was when we first started dating. It happened several times until finally I left him for a short period and then he finally committed to changing. Subsequently, things have been good. I genuinely feel that he's different now. We've rebuilt a lot of the trust but I still struggle immensely. Despite being faithful for an extended period of time (over a year) I still find myself checking up on him. Looking through his fb, emails, and texts. I also find myself obsessing over old partners. I have even gone through and read old Facebook messages with women he has slept with despite the messages being from a year or more before we started dating. I don't know why I can't let go of our past or his past. My sexual history is extremely modest (3 previous partners) and his is not even close. He lost count and is still friends (on fb) with multiple exes and old lovers despite me asking him not to be. Is it unreasonable to want these conversations and friendships to be gone? He also has old girlfriends phone numbers in his phone. He protests that they were primarily friends whom he only slept with once but it still bothers me. Not only do I not know how to move forward but I don't know what's reasonable to ask of him. Please help. 
It's not that he's communicating with anyone - he just is still Facebook friends with a couple women who I know he has slept with before we met. :/