Also, I was at another job when the head director was obviously trying to run me off. I finally told him that "I couldn't be brow beaten into submission, but I could be cheered on to success." After that he tended to back off.
Time to start keeping a spiral bound notebook and start documenting what is going on. Sit down for a few minutes every night and journal what you did during the day. Include all kinds of things that happened, not just interactions with HD. This may help you focus on other things that were positive in your day as well as keeping a record of dealings with HD.
Who knows, maybe you wind up running him off (you just smiled, didn't you?!)