Oh my gosh. Coming from someone else who was smacked around quite a bit, I am so sorry about what happened to you. I have the utmost respect for you being able to leave that situation.
I may not know you, but I already know you deserve a lot better. Though you may know that in your mind, you still might not be convinced of that in your heart.
As hard as it may be to "feel" this, you have to know in your mind that you did the right thing by leaving him. I want you to bookmark this page, and come back and read this every time you need to remind yourself of what you GAINED by leaving that situation, when your heart won't.
Love can be a strange thing. Being used to something can be a strange thing too. Even when it's a horrible situation, when you're venturing into new territories, the "comfort" of knowing certain things about the past, as horrible as they might be, can still be in a weird way, comforting. It's familiar territory. It's your life, and an important part of what you lived through for a very long time. This will stay with you forever, and it's had an influence on who you are and who you may become.
I'm reminded that there are stories out there; when slavery was more popular, there were slaves who were beaten and treated worse than animals. But if the rare gift and chance at freedom came, many of these slaves still wanted to go back to their "old" lives and even their old "masters," verses facing the "uncertainty of freedom." It was the only thing they knew. Things, as horrible as they were, were still familiar, and in a way, "comforting" to some. But it took the strength of many courageous people to stand up and demand that this sort of thing should never happen. And it really changed things for the better.
Never EVER consider going back to him! He needs counseling, among other things. You probably should look into counseling as well, but not with him. I'm sure you're familiar with the phrase: Once a cheater, always a cheater; well, you need to have this philosophy in mind when it comes to abusive people as well. No matter how convincing his apologies might be, repeat to yourself that you must never let yourself be with him again.
There are all kinds of great guys out there who would never even THINK about abusing any woman.
If you're still in honest fear of him, you need to let the authorities and any significant family members know. Your safety and health are paramount. If you need to move, move. If you need to seek legal counsel, do it.
I wish you the best, and I'm praying for you and your well being.