As a retired member of the law enforcement community, the living arrangements you have described might very well be construed as common law marriage. A peace officer will not have the ability to evict or force a person from their home if they have been living with a partner......... sharing rent, sharing bills, somewhat living as a "married couple".
This will be a civil problem that you most likely will have to take to the civil authorities in your area. Take your lease and a letter from your landlord if you can obtain one and present to the civil authority to obtain an eviction.
Legally your landlord cannot evict one of you but must evict both (for breaking the lease if a second party was not allowed to take up residence with out landlord's permission). Common law marriage does have different requirements/definitions in each state, so again I would consult with the local civil authority.