Thumos, I wanted to address the "mature view of casual sex" concept a bit more, but not in the context of a TJ over on that thread in General.
Based on what I understand to be your timeline, there was a period (I'm estimating about 18 months plus or minus -- more or less June, 2016 - December, 2017) during which your WW was exceptionally cruel to you. She treated you with outright contempt. You have outlined the extreme degree of gaslighting during the actual A, and the heavy-handed bullying to try to force you to rug-sweep after.
As to the gaslighting, what I've learned from recent posts is that the AP was a social friend who was regularly at your home drinking wine. What I am inferring from this is that he and your WW were openly flirting and courting, right before your very eyes, and as you protested about this, your WW beat you into submission via extreme gaslighting. When you were away for work, realized the precise moment they were at your home fucking, even to the point of texting the two of them at that time, she had to know that was exactly what was happening. My view is that she took some pleasure rubbing your nose in it.
The "mature view of sex", in context, was a continuation of this. She really did treat you with contempt. Her intent was to make you feel small and insignificant, unworthy. A comment like that might arguably have a place in a discussion between a single man and a single woman about her casual sex with other men, before meeting the man she is involved with. It is totally irrelevant to a situation where a spouse has extramarital sex.
As discussed in the other thread, if it truly was "meaningless", and if her view is that a "mature" view would consider extramrital sex to be no big dealas long as it is meaningless, then why did she hide it? Why not just give you a heads up that she is doing the deed and assumes it's okay with you.
Furthermore, I sincerely doubt it was meaningless, as she has said. This was a man she knew for some time. She was attracted to him, flirted with him in front of you, in your home, and built up an emotional affair into a physical affair with. She decided that sex with him was worth the risk of losing her marriage to you. This is a giant decision for any married person to make, but in her case, where she knew that you were acutely aware of and worried by the obvious signs this relationship was moving dangerously in the wrong direction, it was especially significant. Shopping at Victoria's Secret for the lingerie she would wear. Continuing with the sex even while you were texting her in a manner that made it obvious you knew what she was doing. He was a boyfriend/lover, and the sex was something she very much desired and craved both emotionally and physically, to a degree that she was willing to give up her marriage for it. She is lying if she says otherwise.
The "meaningless sex" comment is also belied by the extent to which she went to preserve and protect the cocoon of intimacy that she created with her lover from discovery by you. She opened up your marriage and invited this man in. She revealed much of your marital intimacy to him, and berated and demeaned you, to him. But she has not done the obverse. She has, to date, steadfastly protected the intimacy she created with him as something above your marriage, and I have not heard you make a mention anywhere about her demeaning her AP to you.
Thus, though I say in General that it was part of her effort to browbeat you into rug-sweeping -- which it was -- it was also part of a larger campaign of emotional cruelty. It was also a part of her process of creating a cocoon of intimacy with the AP. She literally shared more emotional intimacy with him than with you, and she has, to date (approximately three year anniversary of Dday), preserved and protected that intimacy. Contrast that to the easy manner in which she allowed the AP into the marriage and shared with him all manner of intimate marital details.
I'm gathering that stopped some time around the end of 2017 (1st Anniversary of Dday), not because of any epiphany by her, or any healing, but mostly because you simply shut up about the A and she then coasts along in the status quo. Hence, the Plain of Lethal Flatness during 2018, leading to the second anniversary of your Dday.
It was some time not long after that when you began posting here. You are now approaching the third anniversary of your Dday. You have explained how your WW has taken steps to behave as a good wife: taking you to events that interest you; initiating sex; doing domestic stuff unbidden. These are all normal things any good spouse would do. You've also described her as a generally attractive woman, both physically and in terms of her personality.
You have not described anything she has done to help you heal, other than the ridiculously protracted disclosure theater she is dragging you through at present. From my point of view, your trauma is the elephant in the room in your marriage. Without some affirmative steps from her to acknowledge that she has injured you and that she has a role in healing you, the marriage cannot progress. On this point, all I recall you mentioning is her dismissive statement along the lines of "I'm sorry for my contribution to the state of our marriage."
On that last bit, I know you perceive your relationship with your MIL to be good, but your MIL has also recently made a comment about the state of your marriage suggesting she also views it as "not good".
It's almost as if your WW views your trauma as some sort of MacGuffin, a device that is currently propelling the drama of your marriage, two protagonist spouses trying to work through the issues of a troubled marriage, but in her mind the A and your trauma ultimately has no separate meaning, so if she goes through the disclosure theater that she has spent the past 3 months framing, then it will be done.
I do wish you luck. My gut, though, is warning me that this disclosure process will not bring the catharsis that you seek. It will not bring a light of realization to her eyes that she must take steps to help you heal.
[This message edited by Butforthegrace at 1:49 PM, December 4th (Wednesday)]