Teen boys pls help

So I was in a "relationship" with this guy (we're both 16) and we were talking, not necessarily dating but on the way there. We were sexually active, and we cared a lot for each other. But earlier when we first started out talking I found out that he went and did the do with another girl (his ex, my friend) yikes! So when I confronted him about it he shrugs me off, saying 1. He "didn't know what we 'were'," 2. "Thought it was okay with [me]," and 3. Thought I "was talking with other people too." Mind you that this is my first relationship, sexual or not, and I made that clear several times. I felt disrespected. Made a fool of, even. Not taken seriously. I solidified those feelings towards him when I asked to be just friends later on, after trying to forgive and forget didn't work out too well and I was just uncomfortable due to the emotional barrier I had put up. But now, even after a period of being good friends and that working out well, we've fallen back into the same patterns of when we were talking. I've asked for some more space than before and to stay friends no matter what happens physically because I genuinely enjoy this guy's presence in my life. I care about him a lot. It's just that my trust isn't there quite yet where I would feel comfortable in a dating situation. But a physical one is something I'm totally ok with. I just don't want him to catch feelings again because I know for a fact that I can never reciprocate them at the same intensity as he does because of what happened. I just ughhajwjswhwhwh I hate boys they're gross what do I do how can I communicate better or make this comfortable for the both of us (preferably a situation where I don't completely cut him out of my life case I tried that and it didn't go so well lmao)