In your case, the two people who signed the lease is NOT 50/50 responsible. Each party is 100% responsible. That measn, if one of person did not pay rent, the other has to pay the entire rent because the landlord is not just going to take 50% from one tenant and sue the other for 50%.
The best thing is to speak with the landlord privately and ask for help, you may get lucky. If not, you are stuck.