Not about money in my case, but similar stuff happens too. I just stand my ground and say as calmly as I can (with varying levels of success) “I’m sure X happened this way” we don’t discuss it often, my dad usually just keeps up believing stuff happened his way, and we leave it at that.
It’s really tiring to just exist inside your own head.
I’ve described it before as a box filled with a bunch of bouncy balls just bouncing off on every direction, off the walls, ceiling and floor, all the time. Every one of those balls is a thought, it’s really hard to hold onto just one, it’s hard to keep one once you’ve caught it.
When I’m resting usually I just put in some youtube video/TV show/audio book and play some mindless game for a while. On the outside it looks like it just played solitaire for 3 hours straight, but on the inside I’m just trying to follow one line of thought while keeping the rest of my brain occupied and quiet for a second.