How do I break up with him?

I suck at breaking up with people. Like, I don't want to lie and say "It's not you, it's me" because it's obviously him. We barely talk, never hang out and when we do he just criticizes me. I even found someone else who treats me so well and understands me. We were good friends and he helped me through problems with the guy I want to dump. How do you dump someone without coming off as a jerk? Lol