"what happened to her"
I think all of us betrayed would like to believe that "something happened" to our wayward partners.
Maybe a brain tumor, or date rape drugs, or hypnosis by an evil genius, or an alien ray gun.
But none of that is what happened with your WW. Whatever was going on in her brain, she knew what she was doing was wrong. All of the many, many decisions she made, all of the extensive planning, choosing her "slutty" outfits, the trip, Tinder, meeting these men, going with them, taking her clothes off, all the rest.
She did all of that, and she knew all of it was wrong; terribly, terribly wrong.
Why did she do it? Well, you’ll see many reasons posited. Maybe she was looking for validation that she was still desirable. Maybe she was bored, and looking for excitement. Maybe she’s had it with you, and is looking for your replacement. Maybe she’s was looking for more sex, better sex, different sex, a bigger dick, a smaller dick, who knows.
A lot of these reasons, you might convince yourself she’s gotten her answers, gotten it out of her system
The tough one is, is she done with you?
Maybe you’ll stay together, for the kids, for religion, for economics, whatever.
But wondering if she is done with you is tough to get past.
Best wishes.