HELP LAW PEOPLE. Apartment subleasing problem. Subleaser changes word!!!!?

Yes, small claims. E-mail is evidence and strong evidence at that. Your remedy would be the expenses that you will incur for leasing another apartment; the difference in value and all related costs, including the non-refundable you spent. You did not yet have a formal signed contract, but you relied on the promise and acted. That is the legal theory of your case. Meaning. if the court says you did not yet have a contract, you are still likely to win.