When you get a chance, please go thru Bombardier50's thread. I don't know what kind of access you have to reading material over there, but you also really need to read Shirley Glass' Not Just Friends.
You don't have a new wife who has a new friend. You have an old wife who's having an affair. Many affairs are born out of a highly stressful situation that makes the affairee question their outlook on life (or "frame"). That doesn't make the affairee unique and doesn't require special handling. Compassion, yes. Placating, no.
Given your occupation, I know you understand how important it is to deal with the facts on the ground, and how disastrous it is to deal with a sitch the way you'd like it to be rather than how it is.
You've said your W and the OM talk on the phone. How often do they see each other? How much time do they spend together? Do they go to movies together (i.e. dates)? If you told your W that her R with the OM is inappropriate and has to end, how would she react?
Pretend it's two or three months ago. If your W had taken legal steps to separate your finances and accused you of having an affair, would your reaction be to want a fast divorce (which was her reaction when you did that)? Or would you assure her you were innocent and do everything you could to show her that? People who have nothing to hide, hide nothing. Affairees who have something to hide try to put their accusers on the defensive. Do you feel on the defensive, even though *she's* the one in an inappropriate relationship?
Choc, what kind of person is your W? Is she a Christian? Impeccable morals? Active in your church community? Loves her children? etc...
Stop WaitingFeel EverythingLove AchinglyGive ImpeccablyLet Go