Others have said it and I would second that: Plan and organise your exit.
Don't appease, don't confront but don't back down from a fight or discussion. Look for a new job and do your thing as long as you need to or can in the current company. Then quit professionally. If someone asks you why, state that element in the culture don't seem to fit. If someone gets specific in their questions, stay objective and calm while describing the situation that lead you to quit.
Unless they sincerely offer to address the problem head on and offer you to stay on your terms (different department, different supervisor, different tasks, no direct interaction with the a**hole, etc.) don't back down from your move.
I've come to think that gaslighting is a cruel way of social interaction, grown with human evolution.
The people doing it are basically type-a sociapaths towards their victims. It's basically a mechanism of tribe-formation. The old testament and the abrahamic revelation cults much of our western culture is built on are full of this shit. An extended form of it being - of course - modern day fascism.
I read a lot about it lately. I had a strange experience this last half year with a supposed GF of mine and stayed in the 'relationship' just to observe the extreme mechanisms of semi-borderline reality distortion and manipulation she pulled off. I dumped her (the first time I seriously dumped anyone like this) and caught her off guard (she was shocked) but it's interesting that our "relationship" hasn't changed at all, the still behaves like an a**hole towards me, only less so because we don't interact that much anymore.
Social interaction phenomenon like this you should basically take as a more-or-less objective force of nature, and deal with it accordingly. No job in the world is worth putting up with something that challenges your basic inner self each and every step and has you prove your worth as a human every step of the way and has you doubt your self-worth.
You're better of being a bum or a digital nomand than putting up with a job like that.