I <3 Roommates

So I live in a 3 bedroom 6 person apartment, all girls. With those kinds of numbers you would expect there to be some serious drama, and there is, but really only with one of the girls. I just so happen to be the lucky person who shares a room with this girl, who over the course of the semester has bad-mouthed me to all the other roommates and, as we later came to find out, was bad-mouthing all of the other roomates to each of us. Having lived with her for 3 years now, I get the brunt of the blow as she proceded to drunkenly hook-up with my high school crush on my birthday, in our own room, locking me out so I was forced to sleep on the couch, along with telling people I had an obsession with exercise (yes, I've run a marathon but I have yet to hear any doctors tell me that's bad for m body,) and then randomly tell me the day before my birthday (in September) that I owe her $400 and was expected to somehow come up with it that day. She had known about these charges, which were for our apartment in the 2005/2006 year for at least 3 months and then just brought them up one day unexplained and expecting the money. After she forced me into agruing the issue in front of all the other roomates at the beginning of school before I even had a chance to get to know them, I got so frusterated that I left her a check for the $400 just so I could call it even and never talk to her again. Well now, a good 5 months after this, she sends me a letter in the mail, to the apartment where we SHARE A ROOM with copies of paperwork from 2005 saying that I now owe $754 and that the $400 was an arbutrary amount I made up and she refuses to cash checks out of spite and if I fail to pay this money she will take legal action against me. This after she makes me pay another $400 for a parking spot in a parking structure across from our bulding and then never uses the spot that is in our building, but for the 10 minutes she is in the apartment yells at me to move my car (I had not parked in the structure but in the spot in out building) and then leaves, never parking in the spot and has been gone now for a full week. So, when we get a knock on the door last night from someone looking for her, the other roomates and I were a little curious. Turnes out, my roommate had hit this girls car 3 weeks ago down in our parking area and her dad was going to pay her off in cash as to not go through insurance. Only afer weeks she hadn't gotten any money and my roommate and roommate's dad stop returning her calls. Luckily there is footage of her hitting the car from security cameras and luckily she left a copy of her drivers licence number in our room, which we happily copied and gave to the girl. Its just so great when "friends" try to sue you for money you owe them and don't even do the same for others. :)