I rented a room based on a verbal agreement. I moved and paid one months vacated rent. Can I still be sued?

I moved in with 2 roommates in November 2008. The lease is only in one roommate's name and is until January 2010. In February I told both roommates I would be moving out. I continued to pay rent, only because I still had furniture and personal belongings in the room. Now June 29, 2009 the room is empty and I have paid rent for July. They are now threatening to sue if I don't continue to pay rent until January 2010.