Legal Question

So she did not sign the lease? Is she an authorized occupant in the apartment? I mean, is the landlord aware that she is there? If not, then you could get evicted for violating the terms of the lease agreement. If she is an authorized sublet, she is your responsibility. You can evict her by giving her a 3 day quit or pay notice first. Then you can follow the rest of the formal eviction process. And yes, you can sue her for not paying rent.

Hi Aerickson! With regards to your question, if it is between the two of you then that makes you his landlord and gives you the right to go after your roommate for his unpaid rent. The facebook message can be used as an evidence that your roommate promised to pay you his share of the monthly rent. Good luck!