Do you get paid sick pay. ? If yes and you have a clean sick record (if it was me) I would phone in sick go to your GP and tell them you have stress due to work…send a letter to HR explaining every thing you have told us.
It sounds like bullying and NO body should have to put up with it in..
Hope every thing turns out ok for you.. I have been in a simler position 2years ago and it not a good place to be.