Try to think that is way better to be alone than to have an on and off relationship, you're so used on getting back together that you may think that being alone is not better but really it is. It may hurt in the beginning but honestly, i don't think it's worth it. Just try to be strong and think about it every day. Once you get into a healthy relationship you'll see that is wasn't worth it being in one that wasn't stable. If you need to cry and feel crappy then do it, because it's normal but think that you're doing it for your own good. And if you want to go on with your live, don't agree on getting with him again even if he says that he's gonna change and that everything it's gonna be alright, good luck.