I'm going to weigh in here a couple of Denver's comments, especially because he's so new.
want to make sure that you get a very good one who actually cares about your situation. Not saying that the one you spoke to is bad, I'm just saying that I would always suggest meeting with at least 3 before making any decisions. This is not DB advice: I agree with a lot of interviews if you find you have to do this. You will not be able to tell if s/he cares about you.
Second, I hate to confirm what I think that you already know, but your wife is in an EA, at least. I speak from experience on this as well.
No one on the board can discern if this is going on and right now it shouldn't be your focus if you want to DB your marriage.
Your children are grown and are certainly capable of hearing that their mom is involved with another man. Others might disagree, but I would expose A to your children. This will p*ss your W off and there will be backlash. But things aren't going to get better until they get worse I'm afraid. I would also be very clear to children that D is not what you want and that you want to save M. Your W is driving this train and she shouldn't be able to escape responsibility for that, IMO.
This will be detrimental to all involved--espeically your children. You will regret it. Besides DB/DR you can check out Shirley Glass work. Few have success in their marriages when they do this. When they do have succes, it isn't because of exposing. And the children are affected forever. It cannot be undone.
sg Love is PATIENT, love is KIND, LOVE never fails / DB since 2001