Every time they see each other it just rekindles things
Well, maybe absense makes the heart grow fonder. This time she will be there.....and he won't get a break from her. I just really don't think it will last long.
Only you will know when you are ready, but try not to give empty threats, that will only fuel his behavior and cake eating. And don't do something simply to get a reaction out of him. I don't think you would do that, but I thought I would say it anyway.