Sometimes I say to myself, what are you doing in this absurd job? Why don't you go to Africa and help people? But I cannot help people, because I am a hypochondriac.
Either way... you've got to tell him--in no uncertain terms--to knock it the fuck off already. Don't be measured, don't wrap it up in "I" statements, no mewling about your feelings. Give him both barrels: "If you don't knock it the fuck off... I'm going to kick your ass out, got it?" A strategic blowup or two should occur--scream, yell, smash a few things you're not all that attached to--when he slips up. Repeat until his attitude changes or his address does.