What was his response? Did he accuse you of being cold/evil/fake or something like that?
I've been focusing on making decisions based on what I think is right, not on the reaction I expect from someone else. Does this lead to challenging responses from others? You betcha!
He was angry, agitated, accusatory, and tried to use his body to block me from leaving--the most physically abusive he's been--but ultimately let me leave.
Or did he worry about you a lot?
No, not at all. He was focused on how my leaving put
him in an awkward situation: How was he going to buy the expensive piece of equipment he'd scheduled for 9am? What was he supposed to tell the kids? Etc.
Has this event come up in discussions later?
I agreed to meet him to talk in a public place the next morning.
I think if I would do something like this my wife would call me arrogant and abusive and tell me that I'm trying to be someone i'm not and also probably accuse me of controlling her.
Well, he tells me I'm abusive for much smaller (non-existent?) things so what did I have to loose?

And how did
I feel? My adrenaline was pumping. I found it very hard to think straight for a few days; I was forgetful. But I also found it very freeing and exciting: I'd made a change that broke part of our dysfunctional pattern. I felt I had some good power, not just manipulation or walking on eggshells type of stuff.
I also, somewhat uncharacteristically, told a number of friends and family that I'd gone to a hotel in the middle of the night. I was afraid of disapproval, or at least misunderstanding ("but your husband's such a great guy!" "wasn't that a bit extreme?"), but they were very supportive.
Thank you, all.