Document everything in emails that you keep copies of. Offer him to compromise with 4 pm. Repeat that you never made any kind of promise last year. Reiterate that you are giving him exactly what he requested before and do not understand why he keeps changing things. Those statements will look good to a court if it come to that.
Basically, he's yanking your chain - looking for anything to keep the attention going, even if it's negative attention. Don't let him suck you in to conflict.
