I fell in love with someone else while I'm in a relationship. Help?

I have always felt neglected by my boyfriend when it comes to feelings and sharing. I have this feeling that he might not be right for me and 3 weeks ago, we broke up. We stayed apart for only 5 days, until he asked me to talk and then for another chance. He was better and we were talking more, but it lasted for 2 days. Recently I found out that he had slept with 2 guys during our 5-day break up, and although we were single, I was really sad and mourning over it while he seemed pretty excited about it. I don't trust him anymore. I went to a bar with my colleagues from work last Friday and I met a guy whom I met on grind 2 years ago while I was living in my home town and although we didn't do anything, there was this weird but magnetic connection between us. I felt like I was just needy but he keeps texting me and asking to meet up. I can't stop thinking about him, and I can't stand being around my boyfriend anymore. What do I do? Sorry for my bad English