I think you need to tell him you're done with the games and just block him. You're only hurting yourself and the best thing you can do is walk away. If you feel better when he leaves you alone then take that into your own hands. Technology is a wonderful thing. If it's true that he is with someone else and was just keeping you as a backup, why would you ever want to be the second choice? You're going to find someone who is going to make you their number one priority- don't waste your time on this buffoon.