Finish reading your DB book. Make it your priority. Yes, the work is not for wimps.
If I had to guess, your W kind of misses the guy you were before M. Don't misunderstand, I applaud you for deciding not to go out drinking all night. Do you think it is that reckless, kind of crazy or irresponsible times that she misses with you........or does she miss something else that she would consider attractive before M?
Don't believe all that stuff she's saying about why she wants to be with OM. Right now, you really cannot believe anything she says.
If she has told her cousin that she thinks it's attractive the way you left.....then that tells me she does not want your soft, sympathizing style you used when discussing her excuses for being in an affair. It can be a turnoff for some wayward wives.
I feel sorry for men trying to figure out women. We say we want a sensitive guy, right? But if you get too soft, we don't like it. We will start doing little things here & there that push your buttons, b/c we want you to stand up to us. (Not that we are going to tell you, b/c you are suppose to read our minds, or automatically just know these things. ) Anyway, if you back down and let us get away with our little signs of disrespect....then we get worse. Our behavior toward you gets much worse. We want our H to be stronger than we are, and if he's not.....the MR is not going to be very happy.
Let me share what I was told when I first arrived on the board. At the time, I was in an A. I demonized my H and was telling how my emotional needs had never been met, yada, yada. Long story short, the LBS's told me that NOTHING could excuse an A. And I would think, "I'm not trying to excuse it, I'm trying to tell you about my crappy life". See how rational a WW thinks? That's what I was.....a wayward wife. Bottom line is this.......even if you are a very compassionate, sensitive H......she is in an affair. It is wrong. Every time I tried to explain myself.....I was told that if I was that unhappy, then the decent thing would have been to give my H a divorce, and then find another man. It doesn't matter how the A started or why it started.....it's still wrong. As bad as I hated to admit, I knew in my heart they were right. I could not excuse my behavior by pointing my finger at everything bad in my life.
If she had gone to you with a heart filled with remorse and asked you to forgive her......then to be able to do so, would take a loving and sensitive man, IMHO. However, if she tells you she has no intentions of ending the affair......that is kind of like a bully putting the chip on her shoulder and daring you to knock it off. May be a crude illustration, but maybe you'll get my point. In other words, it's as if she's saying, "I'm going to continue this affair b/c it makes me feel good.....so, what are you going to do about it?" Not a good situation. With you walking out, your actions are saying that you will not support infidelity in your M. In other words, you've knocked the chip off the bully's shoulder, so now you will see if she counter-dares you or not.
It is not about what you feel should work in your M. It is about doing the work that gets the right results. Do what works!
) Anyway, if you back down and let us get away with our little signs of disrespect....then we get worse. Our behavior toward you gets much worse. We want our H to be stronger than we are, and if he's not.....the MR is not going to be very happy. 
See how rational a WW thinks? That's what I was.....a wayward wife. Bottom line is this.......even if you are a very compassionate, sensitive H......she is in an affair. It is wrong. Every time I tried to explain myself.....I was told that if I was that unhappy, then the decent thing would have been to give my H a divorce, and then find another man. It doesn't matter 