My roomate left without notice to the landlord?

Our lease ended as of august 30, 2009. I was out of the country (vacation) from June 14 until August 15. I paid my rent and everything. And i filed a notice (letter of intent to vacate) to the landlord. When i came back from my vacation, i found out that my roommate has left the apartment (she moved out all her stuff). i checked with the apartment management, and they were shocked to learn that she moved out without notice. I contacted her that day and she did not answer her phone. So I had to clean the apartment all by myself (and i had a sprained ankle too!). She left the bathroom and kitchen filthy. i had to clean out the whole place including her bedroom. The apartment management sent me the security deposit check after 2 weeks. I had tried to get reach of her, but i could not. On October 30, she emailed me and demanded me to mail her her half of the deposit. She even called me a thief. And that day her brother called my dad and he threatened to take me to court if i did not pay her. i was baffled. Not once has she called me. Should I give her her deposit back? Or should i keep some of that money- for "cleaning fees"? Help!!