Ontario-Roommate Abandoned Apartment
	
	
		Beginning in April 2007, myself and 2 roommates signed a lease on  a 3 bedroom apt. It was a one year lease, and then month by month from then on.  We all graduate this April, and naturally planned to give our 60 days notice quite soon. My one roommate, however, determined that she wanted to move out at the end of this month. Without talking to myself or my other roommate, she spoke to our landlord that she wanted to move out, and our landlord gave her a transfer of rent responsibility form that, once signed by all 3 of us, made my roommate and I responsible for her share of the rent. This form came into my hands at the end of January, as she submitted it without discussion or our signatures for some reason. Naturally, the landlord brought it to me, requesting myself and other roommate sign it to complete the paperwork. My roommate and I were stunned to see this, and simply told the land lord we had never been consulted and would not sign to be responsible for her rent. Two weeks ago, the same scenario repeated itself, and we again declined to sign it to our landlord. We confronted our roommate, explaining we would happily end the tenancy in April, as originally planned, but would not take over her share of the rent payments for the time being. She was insulted and stated that 'the land lord already said it was okay', and questioned why she should pay 'just because we wanted to stay later'. We explained that we had not signed the release of responsibility, and she replied that she would talk to our land lord the next day to straighten that out. When we came home the following day after a full day of class, her room was entirely empty and she was gone, and had refused to sign the 60 days notice agreement. 
We are at a loss as to what our options are to do in this situation. She is only owing one month of her share of rent ($300). Do I cut my losses, pay her share and sign the release forms so that we can still end our tenancy on time? Do we submit a form to end tenancy without her signature, not pay her share and propose she has abandoned the unit? The main issue is we do not want her lack of paying rent to affect our credit rating. 
It seems unfair to let her get away without paying, but I do not know what else to do.