Kalobaby,
I'm sorry you have to go through this. Five years is a long time and I'm sure you think you have a lot invested in this relationship. The only thing is that, basically, your whole life with him was based on lies. It wasn't a healthy relationship, because it was not equal. As you said, you built your life around him. For five years he has let you do this and what sacrifices has he made? He still has his wife, his family and you. It's not fair for you, and yes, you do deserve somebody better. You need to find someone who will put you first, who doesn't manipulate you, or string you along. I think you should look at it like this; this man took five years of your life. I'm not saying that these years were wasted, but they were invested in someone who didn't truly commit to you. I know he says he doesn't sleep with his wife, but do you honestly believe that?
I know it's easier said then done, but you should just cut him off. You don't need to explain to him, why. I'm sure he'll get it... If you have to have some type of closure, though, write to him. You can say all that you want, as long as you want with no interruptions, or excuses from him. Be strong and realize that you can do so much better, and don't ever settle for less again.