I just want to move past this 💔

About 5 months ago I found out my boyfriend cheated on me. I left him for 3 months and 2 months ago I decided to try and work things out with him and see if maybe we could do this again. Well he's been doing really good and just being great to me and trying so hard to fix things and is always apologizing and telling me that he should have known what he had before he fucked up our relationship. He is genuinely trying and that's not just coming from me because I'm with him I have friends and family that have told me that they can see that he's really trying to fix this. But for some reason no matter how hard I try I can't get past it. I don't talk to him about it at all but I still think about everything! It's even worse when we're having sex and sometimes I get the thought of him having sex with this other girl in my head and I have to fight myself so hard to not cry. I know he's trying but how do I get past this. I love this man more than I've ever loved anyone in my life and really truly want this to work but how can I for the sake of my wellbeing get over this or at least stop thinking about it so much. 😭😭😭💔