Hi zombiette,

Sounds like you've got a really bad (incompatible) roomate that you're living with.
(Join the club, same here. I'm in residence)

How many people are you sharing the apartment with? If its more than just the one girl, can you hold some sort of meeting and set up some ground rules?

Or is it possible to talk with your landlord into having him/her intervene and tell this girl what she can and can't do?

Sorry, I'm just brainstorming ideas. I hope you feel better today, but if you want some more help I can try.