OPINIONS PLEASE

So I really like this guy. I went to prom with him last year and we dated for awhile until I said I needed some space. He told me last week that he still has feelings for me. He told me that he wasn’t going to break up with his girlfriend and that he doesn’t like me but he has feelings that have never gone away. I still have strong feelings for him. Should I tell him? I don’t want to ruin what he has with his gf, I think he would break up with her but Would that be wrong?? I know his feelings are strong too.