My boyfriend's sister owes me money, how do I get her to pay?

So I made the mistake of moving in with my boyfriends sister sabrina. She was an ok roomie at first. Then the bitchy side came out when I told her I couldn't afford more than 500 dollars a month for rent. So then my boyfriends other sister came up for a "visit" from texas. She brought her three dogs with her and they were all invited to stay for a month unbenounced to me. It ends up that she is having "problems" with her husband so her stay extends itself to unknown. I am soooo annoyed at this point that her 3 dogs are pooping and peeing on the carpet in our place.I put down 500 dollars as a deposit to live there and HER dogs are ruining my chances to get it back. And then her husband comes to live with us while they look for a place to stay. I am so pissed that I decide it would be best for me to move out and take my name off the lease. Well I come to find out that the deposit must stay with the apartment as long as people are living there. So I draw up a contract with the other sister vicki which took her a month to sign. I at least have that. But I moved out on july 15 2008 and she still hasn't paid me. My boyfriend is stressed out because of this conflict and now I don't know what to do. And I hate that this b vickie thinks she can just walk over me because my hands are tied. Does anybody have any advice on what to do besides small claims...thank you soo much