KLM- You sound like a very caring father. I dont have any kids and I am not married so I dont know exactly what you are feeling but I do sympathize. However, my parents did do an intervention with some family and friends. It took me by surprise because I specifically told my mom that I was going through some things and I just wanted to be alone and take a little vacation. All I meant by that was that if I didnt call for the week, I didnt want them to panic and know that I was alright. What ended up happening was the tricked me and all were outside my place including the interventionist. What was going through my mind was anger and shock. I wanted to sort things out on my own. That might have not been the best solution but that was what I was going through.
They sat in my living room with their letters and started to read them to me. I didnt listen because I was angry. Plus, I kicked the random interventionist out of my place. I felt very uncomfortable with him there, especially since this was a private matter. After I refused to go to the rehab, I immediately packed all my things and lived in my car for 7 weeks. Yes, I felt lost in my head and I didnt want to talk to anyone. It just made the situation worse because my parents were now full blown worried about what was going on with me. It eventually took another bad incident to finally accept to go to rehab. I just ran out of excuses for my drunk behaviors.
My advice, as an alcoholic who has been there, is to let your soon make the mistakes and when he is ready to change, you will be right there to help him out and be the father that you are. I hope my experience will give you any new insight as to what your son may be going through. Good Luck.