How to deal with irrational neighbors?

I currently live in a three-flat apartment in San Francisco. My landlord is in her late 70's, speaks broken English, and lives above me. Her son who is in his mid 40's is jobless, has drug problems, and doesn't leave the house and is depended on by his older mother for any maintenance issues. He is full of rage and it is beyond difficult to engage him in a conversation without him hanging up on me or slamming the door in my face after calling me terrible names. He's like an animal. Not human. Recently, he sprayed the outside windows without talking to me about closing my then opened windows. My IHome speaker system was completely drenched and is now broken. When I left a respectful note to my landlord (his mom) he wrote me back an awful email stating to come to him with my @#$%^& , not his elderly mom. His note back was on the brink of verbal harment. What do I do? I feel scared in my own home. Do I file this with the SF tenant board? the SF police? HELP?! While most would say just move, I truly love my location, space, rent cost is amazing...i'm really stuck.