Since I am the one guilty of multiple A's and she is in one just to get some connection and love and acceptance that she was not getting from me I have not done a thing about that or spoken a word about it. It came up at the intensive that she hadn't spoken with him in a month but I know that's not true, facebook, email comm continues and they see each other at work and maybe after like they did before she admitted it. I intend to say or do nothing about that. Is that correct?
It does change the dynamic a bit because you've had multiple As yourself. It still doesn't mean you have to live in an open marriage, though -- your position should be "I realize that what I did was wrong -- intensely wrong -- but I'm working to correct that. I still value myself too much however to be willing to live in an open marriage."
But in your case, I wouldn't INITIATE that statement. I would probably only focus on maybe not allowing her to lie to my face openly. If she does, just put your hand up in the "stop" position and say "Look, I've been no saint but please stop it -- we both know you're lying to me right now, and it's very disrespectful. I know all about you and ______, and because of my own infidelity in the past I've said nothing, but that doesn't mean I'm going to stand here and let you lie to my face about it."