Ask a landlord-tenant lawyer and get answers ASAP
Hi - my name is XXXXX XXXXX I'm a Real Estate litigation attorney. I'm very sorry for your trouble with this situation, and I understand the anxiety that accompanies a matter like this.
You've done everything that you legally could do to gain the right to assume the lease and continue living in the apartment. Because you didn't prevail in your actions, and because you were never actually the tenant of the property (didn't sign the lease), then you don't have a legal right to live there, and if the owner/landlord wants you to vacate, then you are going to have to comply.
The ONLY way you would be able to remain is if you were able to work out a deal with the landlord that would allow you to sign a new lease, If they will not agree to this, then there's no way you can legally remain there.
I'm sorry that the news isn't better, but I am trying to be honest with you about the law and how it applies to you.
Please let me know if you have any additional questions.