As much as I would like to believe that everyone changes for the best, that doesn't happen. This man has made you miserable for years and never bothered showing you what you meant to him, but now that you want out he gets on his knees and makes all kinds of promises?

He won't change and he took you for granted all this time because he knows he has this power over you. Like Bill3 said, once he feels you're secure again in his life, the old behavior will be back.

I understand that you love him and want to give him this chance in hopes that he's saying the truth. I've done that before, and it ended up with even more pain and destroyed any hope I had in ever talking to him again.

I think it's time that you're a little selfish and worry about yourself. It's time to let your head win, not your heart. It's so hard, I know. You don't want to walk away, but you need to. And often what we want isn't what we need.

Good luck and wish you the best!