I, the master tenant, recently took on a roommate. I paid $1675.00 (79%), and he paid $450.00 (21%) of the total rent. He lived in my apt for 10 days and moved on the 11th. He was a nuissance as he slept all day and tackled chores, i.e. laundry in the early hours 12:40 AM. So, due to our different lifestyles I returned the balance of his rent, minus the 10 days. He now wants to sue me. What are his rights over mine?