How do you get over someone when you are the dumper?

Long story short, I fell in love with one of my best friends. It was wrong, he is taken, but it just happened. He proclaimed that I made him happier than anyone he’s ever met and was willing to take the steps to be with me. (This never happened, but he does spend more time with me than her). I don’t know why I was thinking this would end up well. I suppose I was dreaming up a sort of June Carter/Johnny Cash romance.

One night he ended up slapping me, the first time it’s ever happened, during an argument. He apologized profusely in person and several texts. However, he is also insecure and tends to want to be with me 24/7 and gets jealous around my male friends. I would say he is possessive. That night I decided it was the last straw. Through counseling I realized he was abusive. I guess I’m still in shock, someone I’ve cared for for years and reveals this side of them only when we begin to date. I would not be surprised if he has already been sleeping around to deal with the break up, and it makes me even more agitated.

My problem is, I’m trying to move on. I miss him so much though. I want him to get help and my counselour says he has to do that on his own. I try to remember all the negative things about him and what happened but I feel like I forgive too much. I miss our friendship. I miss my best friend.

Has anyone gone through a situation like this? I know I made the right decision but I feel like I’m still holding on to a glimmer of hope.