How do I get my name off the lease if roommate refuses to sign roommate realease form? Is that required?

I was living in an apartment with an old friend when all of a sudden once I moved in he became very rude, made me feel extemely uncomfortable, he told me I shouldn't have moved in, I had to stop him from killing himself, he was even talking to a girl that had threatened to physically harm me. I lived in the apartment not even 3 weeks before I moved out. I left when he had been out of a town for a couple days because I didn't trust his reaction if I had told him in person. I was barely sleeping, barely eating, was beyond stressed. He practically ran me out of the apartment and now refuses to take my name off of the lease. The apartment complex refuses to do anything and now he skipped on the lease. There is a $4,000 bill that is coming to me because they don't know where he lives now. Is there anything I can do to get my name off the lease and get away from this debt without having to pay? I feel it is unfair since I paid my full month of rent and bills and I was only there for 3 weeks.