Agreed. OP didn't like the characterization of being a "bad culture fit", but to me, spending multiple hours to build a site, purchasing a domain name, and promoting it all over the internet is exactly the kind of pettiness and poor judgement which _would_ make a bad culture fit. I would never want to work with someone who would be willing to write up public manifestos about petty coworker drama.
OP was definitely mistreated, but the mature and correct thing to do is to move on and find other work. Use it as a story for the "conflict at work" question in an interview, but otherwise, put it behind you.
It's also been more than a year since these events and OP just registered the domain three days ago. Reading quoted chats in addition to the OPs statement "At this point these conversations felt so weird that I started screenshotting the strangest ones" makes me think they are still holding onto these screenshots. I think it's time to move on.
OP was definitely mistreated, but the mature and correct thing to do is to move on and find other work. Use it as a story for the "conflict at work" question in an interview, but otherwise, put it behind you.