If your WW and OM work together, it will be extremely difficult (if not impossible) for her to ever end the A. Even if there is no PA, an EA would continue (at least for her). An EA for women are very serious and should not be taken lightly by the H.
Have you read about PEAS? It explains, scientifically, how the brain if flush with these "new in-love feelings" that equate to a pleasure drug. The person becomes addicted to that sensation, as though they were addicted to a drug. She has to separate herself from her drug of choice (OM). She has to go cold turkey, b/c tapering off doesn't work. Every time she sees him, hears his voice, or reads a TM, it's as if she gets a fix. Then she has to start the withdrawal process all over again. And, she will go through withdrawals if she really ends things with him.
You need to realize a WW is very talented at twisting things around to make it seem the H is at fault. It takes the spotlight off her and shines on him. He suddenly feels guilty or frustrated b/c she has him spinning. Your WW did exactly that when she accused you of not checking in with her. It was to take the focus off what she had been doing while her H was away.
Whenever this happens, don't fall into that snare. Stay firm, calm, strong, and remember that you were not the one who has been unfaithful. The burden of proof is on her! It is her responsibility to show she can be trusted again. It is her responsibility to be accountable for her whereabouts and actions..........not you.
If there is no transparency plan, I recommend you develop one. Otherwise, it is very doubtful you will be able to move forward in a healthy MR. Have you asked her, without any notice or warning, to let you see her phone (before she deletes the TM)? If she balks or tries to erase everything before handing it over, then she's still contacting OM.
There should be no privacy or secret R's in a M. Know what I mean?
Nothing, and I mean NOTHING will work until she ends the A. Until she is willing to end the A, she will not want to cooperate with you to work on the M, and she will not truly feel remorse.
The way I see it, the two of then working together is the biggest stumbling block to her ending the A. Stop blaming yourself. She was not forced into an A.
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!