A hot mess

Basically guys, I was going out with my ex for a year and a few months, I took his virginity n he took mine and I love him to bits. We broke up for a few months and I have this side ting that’s been messaging me for over 3 years like he’s always liked me but I never liked him. Anyway I ended up have sex with the boy but I don’t feel anything for him like literally. I did it because my ex was talking to my ex friends and meeting up with them and all sorts. So when me n my ex saw eachother at a party we started speaking n he added me on snap, when he did that I decided to tell him that I had sex with this boy n he was soooooo angry. He was like he doesn’t know if he can forgive me. So I’m like okay we can work on that or whatever, so then the other day I rang a girl he met threw me because she kept screenshotting my story n I asked her if she is speaking to him n she was like yeah they’ve been talking for a while, for a 4 months, baring in mind we broke up 2 months ago, therefore he must’ve been talking to her at the same time as me.

Now I don’t know whether I should continue trying with him or should I just let it go??

UPDATE

we ended up getting back together and we had sex. After that happened we were fine and a couple months later. He told me he had chamydia which he had got from me because I had sex with another boy. He got angry again and didn’t speak to me for while. After a month. He was fine again but something was different, I had slept over his house a few weeks ago and I saw a text on his phone and he was talking to another girl. He told me he was just doing it as a joke with his mates. So I left it. Now we’ve just been going back and forth and arguing every day because he can’t get over what I did last year. Like it’s literally going nowhere. Do you think I should just tell him that we should end te relationship?

A summary of how we are tbh