You do not not NOT want this guy back. He is more than a manipulative b*****d, he is a user. He will wring every last bit of what he can get out of you, and then he'll leave you. He will use whatever bait he can to get what he wants, and he knows how to play the emotions game. He may even pretend to be "changing" so that you won't leave him until he's done with you.

You do not want to get caught in this one. You never, ever want to get stuck with a fixer-upper as a significant other. Either he's good for you now, or he isn't good. There are no adjustments you can make. He's not going to change, and you don't want to be the one to try.

Go cry your eyes out, indulge in an entire tub of ice cream. Listen to angry music. Do whatever you have to do to mark your emotions over the end of this relationship. It's sad. It sucks. You have lost something.

Then chock it up to experience and move on. Without him.