I’ve been looking up a solution myself for years. I ended up with encrypting my note folder with Gocryptfs and synchronize the folder with Syncthing.
Requires quite the setup at first, but perfectly fits my needs (I also use extensively the terminal).
On android there is DroidFS to decrypt your synched folder and read the notes in mobile, but I couldn’t find a way to edit them.

I’d bet it is already happening to them, as they are almost always full of self hatred, bashing more and more because of it, like one runs faster and faster away from a car (I’m bad at metaphors).

This topic always reminds me of this hero https://www.npr.org/2017/08/20/544861933/how-one-man-convinced-200-ku-klux-klan-members-to-give-up-their-robes

I want to see more people like him in this world. But I sure wouldn’t have the guts to follow his steps.

I lived with someone like op described.

He was my father in law and I had no other choice than to suck it up for years. When I left home, he transfered his insane behaviour to his own daughter, who eventually went no contact.
Nobody would believe me, he was so good at making me look like the problematic teenager (good fucking riddance, François).

Some people ARE motivated into making a living hell for you. I know it is hard to even imagine it, because most of the time we live with (to some extents) reasonable people.
But these borderline psychos exist and often target those who are hardly believed by others.

Anyway, my advice to OP is as most said on this thread: document everything, up to the hour of occurrence.

Edit: forgot that post was about neighbors downstairs and not a roommate

I never clicked on your posts because I thought they were literally meh random screenshots and nothing more.
Damn was I wrong. You are building the Lemmy museum of videogames.
Thank you!!!