Relationship Dilemma

So I dated this guy when we were both 18. We dated for a little more than 2 years and he finally told me that he feels caged and wants to explore. None of us were controlling or anything of that sort. We had our small arguments like any other couple, and I think we were going through a rough patch because of which the arguments were happening more frequently, and that was when he told me about wanting to break up because he felt he was too young to be committed.

I kinda saw it coming which is why I wasn't mad pissed. Sure, I was heart broken, but I respected the fact that he was honest about what he felt and so I accepted it and we broke up in good terms.

Now the thing is, we are part of the same tightly knit group of friends. They didn't take any sides, and we didn't put them in such a position either. We had to still see each other every week because we hung out in a group, and even though he wanted the breakup, he would still text me everyday and tbh, we weren't dating anymore but we were still each other's best friends. This went on for 6 months. We spoke everyday, nothing physical happened, we sometimes reminisced certain instances, and there were occasional I love yous too. Fast forward to 2 days back (6 months after our breakup), he tells me he wants to get back. I was unsure because I didn't see what would change. And I didn't want to go through one more heartbreak again. I convinced him it's not a good idea but he came back telling me that if we really were not meant to be, we would have lost feelings for each other in these 6 months, or found other people.

What he did NOT tell me was that he flinged with girls I know on 5 occasions in these 6 months. Everytime I even imagined myself with someone else, I would feel guilty cause it would feel like I'm cheating on him.

I KNOW that this is a Rachel Ross situation, and we were not together so he didn't cheat on me. But the only thing that gave me hope about trying again was that in these 6 months, neither of us ever even imagined ourselves with someone else. I cannot help but feel cheated on, even though we were not together. And the fact that he told me this AFTER I got convinced to try again hurts me more.

Am I wrong for feeling this way? How do I get myself to not think about it and give him another chance?