If I knew more about the situation, I could say more.
Me and my boyfriend have been together almost 4 years, and we broke up (for a few weeks at the most) then seen eachother again, aaaahhhh... It was the best feeling I ever felt. Just to hear the way he talks, and see his smile, I had butterflies, it made me feel like we had just met.
But if you were in a bad situation, I would surely make sure hes changed before I tried to persue anything again. People use the "once a ____, always a _____" thing, and I dont believe in that, cause people really do change, not all people, but some.