Well, having been divorced, I can tell you it takes more than one night. What if tomorrow you made an appointment for a consultation with a lawyer to explore your options, or thought about what you would need to do for a trial separation? Several small steps can make that giant leap more manageable.
You don't have to tell him anything or make a big ultimatum. Just quietly go about your business. When I left, he didn't know I was going anyplace until two days before- he was on a massive bender the week I was packing and didn't notice anything was going on until he sobered up. I'm gone and he's still drinking, so I'm glad I didn't listen to any of his bs promises.
Hugs and strength to you.