I was on a lease with my now ex for 1 year (I was the reason we even got approved for the apt in the first place since he had really bad credit/forelosures in his name). At the end of our lease we were to go to the leasing office and resign a new one together. He broke up with me days before the expiration and went behind my back and somehow signed a new 6 months lease without my name on it. I still live in the apt, still have the building/garage access keys, and keys to the apt, my dog even lives there with me. I get mail there and he is now living in the guest room, me in the master bedroom. Now he says he is renting out my room by this Sat and wants me out immediately. Can he do this legally? Doesn't seem right the leasing office just let him sign a new lease without first checking with me, the other tenant. I thought we were going that weekend to resign. Shouldn't they have had some notice from me that I intended to vacate before they allowed him to do this behind my back? Someone seems at fault here... not sure if it's the leasing office or the ex. He was also unemployed and has been paying the rent late the last 5 months at the time they allowed him to resign the lease alone. I would like to keep the apartment because I have a roommate that wants to move in. Also, what about my half of the security deposit and my $500 dog deposit? I also paid rent separately from my bank account directly to the developer of the condo building. So I have proof I've been paying.

... At the end of our lease we were to go to the leasing office and resign a new one together.

...Also, what about my half of the security deposit and my $500 dog deposit? ...
Please do not post the same question twice. Doing so will not make your answer faster or more accurate.

Unless there is something unusual in your previous lease, there is nothing requiring the landlord to let you extend for another year. You do, however, have a tenancy-at-will until either you or your landlord gives the other the proper notice (30 days, usually). The landlord would be legally unable to give possession to a new leasee (your ex) until this has been done.

So it looks like the landlord (unwittingly, would be my guess) let your ex have a new lease. The landlord is required to refund your deposits when you leave the premises in good shape.