Ask your landlord to evict him for you. Work out a deal where you pay only your 1/2 of the rent so that L can evict R for non-payment, but you give L the rest of the rent after R is evicted (without incurring late fees). Inform L that if s/he doesn't help you get rid of R, you won't be able to continue paying the entire rent & you'll both have to leave. If L is reluctant, you might offer to pay the filing fee & have a friend serve R to save money. Also, check the lease to see if one rommie can be evicted for non-payment even if the other roomie is covering the entire rent.
You should also sue R in small claims court for not paying his share of the rent & utilities. Both you & L will have 10 years or so to collect your judgments by garnishing R's wages when he gets a job.
------------------
This is not legal advice and you are not my client. Double check everything with your own attorney and your state's laws.
