That is terrible news, I and several others were suspicious about your sitch in that way. It's very uncharacteristic for your W to be able to ignore your efforts for so very long without another outlet. The good news is that now at least you know why your DB efforts haven't yielded progress, if that's any consolation.
Affair recovery is the worst, and it's very emotionally difficult. If you think DB has been hard so far, it will get harder before it gets better. Not that your W will do anything differently, but that your mind will go places it hasn't before. Now more than ever you need to focus on you. Remember, the EA or PA was not about you. It doesn't reflect on you, and it doesn't mean your marriage was bad or that you were a bad husband. This happens every day to good people. It's a reflection on your W, she decided to do this -- you didn't push her to it. Remember that.
I've learned that it's usually a slippery slope. Your W starts by just being friends with a guy from work, then they start talking about more personal topics as they get to know each other, then they start to feel connection, and before they know it, they're feeling "in love" with each other. Often they didn't plan to go there at all, but it happens. When the marriage at home is not particularly happy or connected, it's harder for them to put the brakes on when they should.
You've shown remarkable resolve to date, this is going to test you again. The good news is these affairs almost always burn themselves out. They are based in fantasy, and that will wear thin. The affair partners feel good when they are together, but when they come home, they have to face you and feel guilty, and lay in bed dealing with the fact that they've violated their own core values. When it does burn out and OM is gone, that's when (in my experience) you can really make progress with DB.
Know too that when it ends, your W will go through a period of grief during which she will be very hard on you. That's probably the worst part, dealing with the grieving stage, all you are at that point is "the bad guy".
Good luck NYCPeter, I went through this too and it was no fun, but after OM was gone, and grieving was done, I was able to turn it around.
--Accuray
Married 18, Together 20, Now Divorced M: 48, W: 50, D: 18, S: 16, D: 12 Bomb Dropped (EA, D): 7/13/11 Start Reconcile: 8/15/11 Bomb Dropped (EA, D): 5/1/2014 (Divorced) In a New Relationship: 3/2015