What would you think about emailing him and telling him that you're having second thoughts, are confused, and would it be OK if you came in sometime to talk about it? Your regular appointment, if that is still available, or another if he has already booked it to somebody else.

He can say yes or no. If he says no, you can try another therapist. He probably won't say no, but I agree he took you at your word. In many ways I find that positive, not telling you what to do.

People DO change their minds in life. It IS therapy after all, I would think he would understand that. But, if he doesn't, you can try another therapist and if he is that rigid, maybe your decision to quit was a good one after all. Won't know for sure unless you ask.