Sub-lease and security deposit issue

I had a 2 bedroom apartment that me and my friend were in (both names were on the lease), and the lease ended in July. However, I had moved into a different state a month earlier, but was continuing to put up my share for the remainder of the lease. The office called us about a week before our lease was up and said a girl wanted to sub-lease so that she could get the renewal rate, rather than the new increased rate. They told me they were going to fax me the paper work, but I told them I wouldn't sign it unless it said that the girl moving in would pay us the full deposit beforehand. They also said that it would not be valid unless BOTH of our signatures were on the sublease papers. My roommate went ahead and signed while I was waiting for the paperwork, but they never faxed it. So they let the girl move in anyway, and she calls me and says she refuses to pay the deposit because the place was dirty. I talked to the apartment complex and they said the sublease was valid, even though only my roommate's name was on it and I never signed, and whoever told me that it would only be valid with both signatures misinformed me. They said the deposit is not their responsibility anymore, and we can't get it from the girl because it wasn't in writing.

The last document I signed was my intent to leave at the end of the lease. My signature was never on any renewal document. Is there anyway that I can fight this and get my deposit back? It seems messed up that I am caught in the middle when I never signed anything at all that said I was putting the deposit in the hands of someone I never met, and also that 2 people at the office told me specifically on the phone that both names had to be on the paper. Thanks for the help.