Oof, that's hard. I hope this is the end of the escalation as well. Just keep at the forefront of your mind, his actions are not your responsibility, and that responding now would only undo any progress you've made. As annoying as this reminder is after it being reiterated so many times already, still.... I would say I'm sorry for reminding you yet another time, but that would be a lie. Rather, I apologize if it's super annoying at this point. Because I get that.

Stay the course. There's a storm on the horizon, but turning around now won't save you from it, just take you further away from the nearest safe harbor. Better to sail straight through the eye.