Someone who drinks into a blackout is not a trustworthy person. My ex progressed to the point where he blacked out every single time he drank. It was hellish to live with someone doing that.
He did so many awful, destructive things. Made our lives miserable. But he never remembered. Woke up every morning with a clean slate like nothing had happened.
Just because you were drinking with him does not give him a right to violate you. My ex frequently used the excuse that I was also drinking (1 beer or a glass of wine) to justify his behavior. Even after I quit drinking, he found all kinds of ways to excuse himself. He doesn't need you making excuses for him (drinking makes you do stupid things), he probably does a fine job of that himself.
And what if he had been sober? Would it still be excusable? What if he blacks out and does something worse? Does being drunk make that OK?
Someone on here has the tag line- unacceptable behavior is unacceptable.
Take alcohol out of the equation and what does that leave?