I started a PhD program in the US in August. My supervisor didn't respond to numerous emails, copied to department staff, for a month. Finally, I got some rather hostile responses -- all caps, abusive language, etc. After that, we had a meeting that was just bullying, condescension and harassment for an hour - they said I was not communicating with them! On top of this, they completely changed the research direction we discussed that prompted me to apply in the first place. None of this is in person, all remote.
The harassment was so bad, I have never experienced anything like it. I want to leave. Flew off the handle accusing me of doing things I did not even do, that were frankly immature, unprofessional and demeaning. Should I file a complaint and leave or just leave or ask for another supervisor? Also there is a disability related issue here which was not allowed to be addressed, and is required by legislation. Needed permission to take a course in my research field from them as grad chair directly related to research and flew off the handle accusing me of not wanting to do any work or complete research properly. Talked to me in dehumanizing way, like I was a child. My current supervisor is also the grad chair as said - so it complicates things.