Although you are contractually obligated to pay the landlord has an obligation to mitigate, so if other apartments were rented, even though yours was not re-rented, that may be a basis for you to avoid liability?
Second, if you are not working, collection may be difficualt if not impossible. You might be a bankruptcy canditate, even if you do not file, and the creidtors may back off if you infer/threaten? For 2 months rent, it might not even be witrth the effort, although the collection aganecy may just make phone calls "threatening" - know your rights under federal and state law as the tables might be turned if the landlord or collection agancy doesn not know their limits.
You might end up with a "bad" on your credit, credit report, etc - you must assess the risk and then determine how to proceed - many do not pay their legal obligations.
If you broke your lease in October by vacating, then the landlord has a duty to mitigate damages by using reasonable means to rerent the apartment. It does not appear that the landlord has done so. Try to explain this to them and if they are being stubborn, you can either pay or not pay and risk a court action.
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