Not sure what advise anyone can give you regarding your AH and driving drunk with the kids in the car. It’s a given, he’s an alcoholic doing what alcoholics do, children or not.
Trust your gut and I hope you have your children in counseling to help them deal with the position of unintentionally being placed in the middle.
My initial thoughts are, I wouldn’t address this past weekend’s incident until the next time they are supposed to be in his care. Say something along the lines of, last time they spent the weekend with you they were upset being in the car with you after you had had a few drinks. Maybe if you have plans that include drinking its best the children just stay here with me so you can do your thing.