My roomate has failed to pay her half of the rent. Is there anything I can do to keep me from being penalized

Yes, we both signed the lease. I know that I am probably doomed because of that, but I was just hoping maybe someone knew of some way around that. We both pay our half of the rent with separate checks each month, so they have proof that I have been paying my half. We both have moved out and are finishing paying the remainder of the lease. Since I don't live with her anymore, I never see or talk to her. Neither the apartment's office or I can get a hold of her. The leasing agent said that she was sending the debt to collection and it would damage both of our credit. This just doesn't seem fair. Shouldn't there be something I can do? Why should I have to pick up her slack?