Advice: Roommate on lease pays no rent and is mentally ill

Unfortunately had this individual put on lease. Paid one month rent but nothing for last 5 months. Ive paid all since. Person is volatile and mentally ill--. Steals any food bought, buys none. Leaves the apt unhygienic, won't clean up. Sent to Strong once but was discharged back home (not to Psych Center, unfortunately.) Refuses to leave. Landlord says nothing to be done except to evict me and roommate. Process will take months. Any help appreciated. I don not think I can tolerate continued occupancy.