Oh my dear, how shattering to have this betrayal thrown in your face, and how terrible for your sons to see and hear what they did.
Having someone drink driving scares me witless at the best of times, as I imagine the guilt I would feel for the rest of my life, letting them drive and doing nothing, if they caused death or injury to others.
Maybe you could talk when he is sober, but I wonder if he would listen.
What thoughts, if any, have you had about getting your boys and getting out of this very hard and unpleasant situation NOW?
Frankly, living with this MAD Max violence, drinking and cheating would be impossible for me to manage, for 1 more day, let alone for 2 more years.
God bless