I've used facebook to completely block people. My husband had an abusive ex girlfriend. But someone she managed to become great friends with my mother in law while they were dating. Every where I looked on facebook, there she was. So eventually, I just completely blocked her. Fun fact, we also used to be friends, too. Point of the story: You have to do what is best for YOU. Not worry about how other people will take it. That's not your problem. You have to change the things you can change and not worry about the rest. And besides, if you completely block him (and I mean COMPLETELY), then you'll never know his reaction

Good luck. Keep taking care of yourself.