Thank you for this. You're right about documenting things because I've realized that it's not always individual actions (though sometimes it is), but often it's the combination of smaller actions or words that makes up the abuse.

The problem with the chain-of-command is that I can't trust his superior, nor can I trust HR. It would all come rolling back down the hill to him and inevitably make things worse for me. I've seen the company work this way before and it's incredibly frustrating. I feel like I'm in an impossible situation-- or that I just can't see the right solution