"That's not a problem, I went ahead and took tomorrow off of my calendar but left on Monday at 12:30. Regarding your email from last evening, I feel as though we have a positive track record of discussing problems and coming to a constructive understanding, and I would expect that we would be able to do the same now. Feel welcome to reach out if you change your mind about Thursday."

The thing about "last evening" was a 2-sentence email I sent saying I was concerned we were at an impasse.

ETA: I imagine he was at least a bit surprised that I didn't reach out trying to reschedule Thursday's session. But as I said to K today. I just needed space from him. Which I think is telling, because normally I want to resolve things (with him or anyone else) as quickly as possible. But I just felt going in there yesterday would not have ended well.