All good stuff.

I find that if you're in a gaslighting situation, the realisation of what's happening is huge because it allows you to yank the conversation back to the point.

In many cases, they're gaslighting to get you off the point. You end up arguing about the "whataboutery" rather than what you want to talk about. Don't let them do that and continue to call them out on it.

Once they see you're not budging from the main thread of the conversation, I can't promise you they'll give up entirely but they'll at least know you see them.