.......seriously, why can you not move past the affair? You are obssessing about it way too much...as I told you in the very beginning, some spouses will never, ever, admit to it...your wife happens to be one...you need to get past that. You keep this sitch in the past, forever bringing up the affair, over and over...your marriage is the problem, you both lack effective communication skills, you both lack listening techniques.
Her affair was a symptom of all that represents your marriage. It was her way of shutting out the pain...yet every day, you bring up the affair...you need to move past the affair. Let it go for your own sanity.
By you mentioning it so much, you keep it alive...yet she was not innocent when you married her...but this seems to give you the power over her...your one-up. Let it go...
If you do get to a therapist, tell all...everything...even if she doesn't go with you.