I wish I knew what to say to help you through this.
I think it's great that he wants to work on the relationship. There are a lot of people who would love to be where you are now.
It will take time to heal. It will take time to rebuild that trust. He is weak, but so are we all. Set your boundaries, and give him encouragement and support.
Someone told me that the relationship I had with my wife is over; we will never have that level of innocent, almost childlike, trust again. But that doesn't mean that we can't learn to trust each other, and now we can see the weak spots in our R and learn how to strengthen them.
Hopefully you can do the same.
Me: 44, Wife: 39 M: 17 years T: 20 years Bomb on 08/25/09 1/13/10: MC started 1/28/10, 2/8/10: More bombs 8/28/10: Wife moved out No talk of D, no movement