Am I in the wrong here?? Please be honest!!

So I was seeing this guy for about 4 months. It was mostly just sex but we would hang out and definitely had a great time together and really liked each other. We were never in a relationship but we did agree not to hook up with anyone else while we were just out of respect (and being clean tbh). One day after 4 months we got into a fight over something incredibly stupid and he ended things out of nowhere. I was very confused and hurt by this and I actually did miss him a lot. But Ive gone through real break ups and it was never that serious in the first place. We were no contact for about 2.5 weeks and I thought we would never speak again. I end up going out on a group date with a mutual friend. I wasnt super into this guy but just having fun with all of our friends. We had a quick kiss at the end of the night and didnt really talk again after. Few days later the guy I was no contact with hits me up saying that he misses me/wants to talk. I end up telling him about the date and kiss thinking its no big deal but just to be transparent. Well, he lost it. He says hes disgusted and hurt and that 2 weeks is not long enough and that I wronged him and betrayed him and he cant trust me and that it "says a lot about someone" to kiss somebody 2 weeks after. I thought I reasoned with him and he calmed down and things were good for about a week but now he is back to talking down on me for it and basically acting like I am trash for kissing someone when he ended things. Am I in the wrong here or is this an over reaction on his part??? BTW we are in our mid twenties not in high school