It is not horrible if you decide to not go looking for him. Let him do what alcoholics do and let him feel the consequences of it. It isn't being a bad person. Maybe, just maybe, he will hit his bottom, whatever that is, and then again, maybe not, but let him figure it out. You can take that burden off your shoulders and the shoulders of your son. That had to be horrific for your son to experience and for your youngest to worry about his dad passed out in the truck. My kids, I'm ashamed to say, were terrified when their dad drove drunk with them in the car. I am ashamed I allowed my sons to ever be in a car with their dad.
Please unpack that heavy backpack of burdens involving your AH that are not your responsibility. If you all had left him at the bar, at lease he wasn't home and you all would have had peace in the house. Use that time to bond with your sons, or talk with them about the elephant in the room and how it isn't their fault. In other words, focus on you and your sons and leave the alcoholic to the alcoholic.
I'm so sorry that happened to you and your family...Hugs to you and I pray you all find peace.