Gail is, as always, correct. Your job as Landlord is to collect the rent in full! The roomat ebreaching lease is not your problem as of now since you still have a tenant there. The current tenant residing in home must pay full rent! He then can sue his former roomate for his/her portion of rent he had to pay until new roomate is found. Note you still must approve of new roomate tenant cannot just bring anyone in. The new tenant must meet whatever criteria old one did to live there. Once done you can then amend lease or allow new roomate to live there paying current tenant. In short sublease