You liked it didn't you?
lol...you really think i liked it? lol
Report that asshole for sexual harassment and extortion or something. Tell his boss that he's forcing you to sleep with him to keep your job. Extorting someone for sex is much more illegal and wrong than smoking weed.
Better yet pull a Monica Lewinsky - let him blow his load on your shirt and keep it. Then demand he triple your pay but don't have to go to work any more. If he doesn't, go to the police and tell them he's forcing you to have sex with him against your will. You have the proof - his DNA on your shirt.
You know you can also just look for another job, find one, and leave the one you're at now.