I am very sorry to hear about what is happening in your marriage. Your post really touched me with it's honesty and accountability.
In many ways, I am your wife. My husband is an addict - 16 months clean now. What you described as life at home was my life except my H was also in an affair.
I apologize if this comes out harshly, that is not my intent. I hope to offer some insight into your wife.
While I never cheated on my H, I can't say part of me didn't think about it. I was pretty insane at the time. I could see what was happening, but he denied it. I was always told I was crazy (both directly and indirectly) and I started believing it. I felt trapped, no way out. Crazy brain thought an A may be the only way out. Then he would leave and I could start over. A lot of spouses of addicts I know have also had these feelings.
That doesn't make the A ok. But when you are crazy, you make crazy decisions. You know that from your addiction too. Just like you understood the drug as a mistress, look at her A like you see your addiction. She is not at the point you are now, she is more like you were in a sober period. She may not be "using" (still in the affair right now - make sure she is not btw), but her mind is still thinking about it, rationalizing, questioning, etc. She is in the "fog" and it will take something dramatic to get her out of it (sound like you?
I see a lot of good here from my perspective though. Like I said, I was very touched by your words. If my H said that to me, I would be overjoyed. That being said, it takes a long time of good behaviors and actions to really believe it. You do not have to have patience with the situation with the other man, but do have patience with her believing you have changed. It will take a while. The more you show it, the less time it will take. Be open with her. Addiction is full of secrets and things left unsaid. Show her you are a safe place for her to be open. Something "dramatic" could be as simple as her waking up one day and seeing how different things are.
That being said, don't hold yourself hostage for your past mistakes. You don't deserve to be treated like sh!t just because you may have treated her that way. Make some boundaries and stick to them.
I would suggest you check out NA as a place to turn during this time. There are people there that have been in your situation and made it through.
All the best to you. I hope you find something useful in my ramble.