Good luck. Part of me wants you to follow through with legal eviction so that he'll have one on record which will make it very difficult for him to rent again and warn other landlords, but often that's not worth the hassle for you if you can resolve it quickly.That's easy: money doesn't leave your hand without an empty apartment and keys in your hand. Change the locks immediately.

Careful recording people, i think your state is a two party consent state

"Massachusetts is a two-party consent state that requires the consent of any individual whose voice is being recorded. Recording another individual’s words without the individual’s knowledge or consent is a felony in Massachusetts. To Massachusetts Wiretapping Statute, G. L. c. 272 s 99, makes it illegal to: [S]ecretly hear, secretly record, or aid another to secretly hear or secretly record the contents of any wire or oral communication through the use of any intercepting device by any person other than a person given prior authority by all parties to such communication..."