Is this MLC? Is there any way this makes sense to her?
What if it is MLC? Does that change anything? Would it somehow make you feel better? Not anymore than hearing she's bipolar. I think you are just seeking some kind of diagnosis or label to give this craziness.
So, she was outed to her family. I don't have details about how the A ended, just that OM slid under a rock. What I am seeing in the information I read, is that she has not changed her mind/heart, and since she's already been exposed then why hold back now? She might as well live it up the way she chooses.......not how her H or family chooses for her.
As I said before, she may have agreed (with you strongly insisting) to go to MC, but it was just lip service to get people off her back at the time. When there is no remorse after you've been outed, there's nothing left but rebellion and resentment. Oh, and she does feel very entitled. If she ever has a doubt, her posse will set her straight. It doesn't have to make sense to her, b/c she running on the high she gets from it.......just like a drug user.
I do not say any of this with a cold heart. If I had not had a dose of the waywardness myself, I would be exactly like you and her family. If it were my sister, daughter, or spouse.....I would think there must be something terribly wrong with her. And if there was one sibling with bipolar, I would probably wonder if she had it. However, I can tell you a wayward spouse can act as if they are bipolar. But there is no medication for waywardness........(in pill form).
So I don't think she ever had intentions of turning around. She sees she survived the heat, and continues going on however she chooses. You may have drawn a line in the sand, but she more than stepped over it and daring you to do something about it.
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!