She tells him the night of 10/01. It is only 10/5. It is Big News, and he could be emotionally flooded.
Guys really do seem to shut down when flooded.
I would not make a rash decision about ending a marriage in a mere 4 days.
She is asking him to consider a huge
paradigm shift in his belief system. And where you draw the line in the sand at a physical intimacy, you do not know if he draws it at emotional intimacy. So he could be feeling betrayed at a level you are not if he thinks his wife has been cheating on him emotionally in an affair of the heart (if not yet the body.)
Dunno if there is anything here that will help:
I think his request for her to chill on seeing your wife is ok if he puts a reasonable, MEASUREABLE time limit. (ex: a month of limiting it to email or phone and not in my face-ness please so I do not emotionally trigger and flood while processing with you.). Saying to end it with wife is NOT fixing whatever is wrong with the marriage or working on whatever issues he has in his personal growth. It's just removing the flashlight thing (rship with your wife) so he doesn't have to look inward at himself or his marriage. The broken is still there whether we shine a light on it or not.
I think her stating she's not giving up her relationship with your wife is valid if she wants to be in relationship with her. But if her relationship with your wife can't hack a month of time out while she sorts out her marriage? What? Your wife isn't worth the wait? Her husband of 20 years isn't worth the courtesy of 4 weeks after dropping a bomb like that? I think she could reframe it and quietly and firmly say "No, I am not willing to terminate my relationship with (Your Wife.) I *AM* willing to dial the volume on that down to email/phone friendship for (time limit?) while we sort our own marriage out first. I want to see a marriage counselor to help us. I want to try to be in relationship with you and navigate new change if you are willing top try. Are you willing to try?"
I think her request to see a counselor to help them navigate the month of intense talk reasonable. Sometimes a mediator is needed. Things were broken before your wife entered the picture. So... let's get on with fixing the broken that was already there.
A month time out to digest the news is not that long. And the only question he needs to find an answer to inside himself by the end of the month is
"Am I willing to work on myself and on my marriage with my wife to embrace this new change or not? Will I go to a counselor to start that process with my wife?"
Is not willing, and it is a total dealbreaker -- move toward amicable divorce then.
If willing to try - then the next baby step to see if he can learn the skills needed / embrace being a mono V arm in a "V" thing with his wife as the hinge.
I don't know if that helps you guys any. Hang in there. It may not be fun to feel but at least it is open, honest, and trying to be as clean as possible. That's still
a Good Thing.