I think you've hit the nail on the head @AMusingChickadee. It's like throwing a fog over you in the hope that you'll be confused enough to forget the things that really happened.Hi, I know this post is a little older, so I hope it’s ok that I respond. Your situation reminded me of one of my own. I wonder if the hot and cold behavior is because maybe on some level they recognize their wrongdoing, but are simultaneously uncomfortable feeling the guilt. At least for very long. Like they don’t know how to process the guilt healthily - so they try a “quick fix” like throwing money or vague apologies at you and expect that to be the last of it. Talking about it in detail to help process makes them have to confront their feelings about themselves too much. So when they see the pain hasn’t magically gone away, they get angry for having to feel the guilt again, so instead it’s easier for them to put it on you for not being over it already. Not sure if that made sense.
What happened with my mother is she got old enough to realise the truth is the truth, and also, for which I am so grateful, she realised she had been wrong. And in turn I got to experience the fact that she actually did love me in her own way, but had made some big mistakes. Of course, the mistakes don't magically stop hurting you, but I can accept human failings - I have plenty of my own. It's harder to accept someone not caring enough to be honest and release you from the web of lies.
Denial is a strong force, and very destructive with stuff like this.