Make a bunch of male friends to help you, jizzing in another blanket and holding down that nasty bastard when you force the blanket through his mouth, preferable while the thing is still fresh... maybe he even would love it, who knows. If he chokes with the blanket..., well, accidents happen.
This reminds me of the one scene in Cujo where the wife's ex-lover trashed the house and then came all over the bed. Hell, he even left a note saying that he "left a present" for her upstairs or something.
When I caught my roommate fucking her latest hookup on my bed, I stripped my bed down to the mattress and threw out the entire set of bedding. Yes, it was financially hard to replace it, but I wasn't about to sleep there knowing what had been done on it.
There's something that you need to hear, something that I need to confess...it wasn't the ex-roommate's boyfriend that exploded all over that blanket...it was...it was...well you see...it was THE BATMAN
Ew. Just...ew. Boil that fucker (blanket or boyfriend, I'll leave that up to you). Hopefully your new situation is better.
Now for a fun story... First roommate I had agreed that there was to be no sex in our room (I naively expected that she'd go to the guy's room or something), then she got a boyfriend and our room became known as "The Rabbit Hutch" because they were fucking like bunnies. When she wasn't screwing her nasty pothead boyfriend or doing hipster things, she'd either be sleeping or crying or watching Charlie the Unicorn. I spent as little time as possible in the room.
After a few months of this, our room started smelling really weird. I just figured it was something caused by her hipster hygiene habits, though it didn't smell like body odor. Then my friend and I watched "Perfume" (main character has super olfaction) and I had an epiphany: the smell was months of accumulated dirty hipster sex odor. I moved out of that cesspool when the semester ended.