Oh! Should have said this am not guessing. I was told all of my last post by a serial cheater. I told his partner what he had been doing, I told him I would, he thought it was funny, she wouldn't believe me. She did, eventually.
After about 18 months she rebuilt her life - he had had no small number of affairs, including 2 sisters, both of whom had a kid by him. She was a totally normal woman, has no idea she had moved herself into a soap opera.
He came to me, angry and very upset that she had moved on. He figured he could tell me as I already knew everything. He was puzzled, couldn't work out how she could act as though nothing has happened. How could she move on, what would that do to their son, etc?
Oh, and would I tell her to stop seeing the new man and go back to being alone and miserable? Yeah, right mate!
About 3 years after that she contacted me. Wanted to meet and talk about it all, put it to rest between us. I told her about my last conversation with him and she was highly amused. She didn't invite me to her wedding but we are now very good, close friends. We don't talk about him any more, well, not unless drunk, or when her son wants to know about his dad (she tells me what she really wants to say, aka vents, and then talks calmly to him).
I've also known a woman who was much the same when her patient DH finally walked away. She didn't believe he would divorce her, let alone cite her affairs as the reason. She was furious... mainly that he had the nerve to leave, make her look bad.
People who cheat have a different turn of mind, I think!