I agree with the blocking on facebook. Unfriending is the easiest way if you are friends with him on there. If it's a way that you keep in touch with others I'd suggest staying there and unfriending him. If you don't want to do that, which I can't imagine why you wouldn't, you can unsubscribe from his posts and they will stop showing up on your timeline even as you are still friends. I say go one step further and block him completely though. That way he can't come running back to you, messaging you because his ex broke up with him again!