Honestly. I don't know. Your dilemma is PRECISELY my dilemma. There is an OM and it seems there is an emotional attraction.
Some on here say: enforce boundary. Some say ignore there is an OM and work on yourself There is probably other advice.
I don't think pursuit is the answer BUT showing kindness towards her and giving her compliments IF you normally didn't do that is NOT a violation of DB/DR. Now if she responds with intimacy that's where the advice from DB/DR seems to go in different ways. But I personally see intimacy as lifeblood of a R. Just don't make it more than what it is "having a good time at the moment". I don't know if withholding intimacy helps if one the reasons of wanting out of the M was because of not getting enough attention. Certainly, don't be overly romantic, begging, pleading, convincing how the marriage wasn't all bad. But I don't think the opposite is always the right thing either.
The defiance is one of two things. I am guessing Sandi2 will come here and say it means you need to enforce the boundary and your W hates that you hold her accountable and don't let her eat her cake. By enforcing her boundary she might be angry but in the end she will respect you. I think a lot of the times that is right.
I will repeat myself that ultimately you have to follow your gut. Maybe she is shocked because she thought she could stick around and take advantage of you while also being in contact with OM. By insisting NC you may get her to recognize she is about to losing something great. Or by moving out she may recognize what she thought was desirable isn't ideal.
If you think you need to make changes to yourself than GAL with her in the home and doing all these awesome things without bothering to see if she wants to join you might help her recognize she is an idiot. In the meantime if there are increasingly nice interactions with each other that to me is a good thing.
And of course, I only accept my wife's explanation of OM as a friend because she is afraid of me and feeling trapped. She has said she knows what is expected of her once we recommit. So while I am taking a risk ultimately I am trying to show my W that I accept responsibility for making her feel scared and trapped. I have noticed changes. I wouldn't be this way if I didn't see them. I would have kept with where I was two Saturdays ago during the session where I said that there is no hope and that I am done and will let her go since she cannot let go off OM. Her behavior after that convinced me that fear was really there and that unless she is an actress she doesn't know what she feels and she doesn't want to rush things. If it turns out that I am being played then I can walk away knowing that I gave it my all, TRUSTED her (when maybe I shouldn't have) and given her space that she asked for and in the meantime been there for her when she needed me and ACCEPTED it when she needed some alone down time. I can respect myself if she walks away from that. If SHE can respect herself that she is only being nice to fool me and really is just biting her time than that is not a person I want to be with. But at the end of the day despite what I THOUGHT... I am finally now acting like the H that she needed all these years. It has been since late April that I begun my self reflection and I had some setbacks (which all connected to her fears and not just that OM was involved).
But it's my gut. (along with MC and a friend who was skeptical about W and is now saying maybe I do need to give it time)