Most Helpful Guy
Breakups always hurt. There's no way around that, and no magic answer.
However, breaking up with this guy is the best thing you can do for him. And you need to tell him WHY, and you need to NOT get back with him, no matter how much he promises to change. He needs to learn that his selfish behavior has consequences, and may he really WILL change. Either way, that won't be YOUR problem - you need to move forward.