I've lived through this once with our older kids and it skewed their viewpoint and mine. I'm recovering, but they haven't started yet. A couple of them are now using alcohol as a crutch also. Our daughter swore for years that she wouldn't drink (having lived with a drunk in the house), but now she does (possibly to deal with anxiety) and her husband (also from an alcoholic family) thinks it's healthy for him to have a couple drinks every night. Alcoholic genetics and environment both at work. Several red flags other than that, but I have to let them take their own paths. I truly am powerless over alcohol and other people's lives.
If my husband were to relapse I would give him an option of going to rehab. If he didn't, I'd let his sponsor and former rehab counselor know so they could deal with him.
Then I'd pack up myself and our youngest son and leave. He's 7, but I would do that even with a teenager. I finally understand our kids pay attention to our actions, not our words. All the years I stayed with an active alcoholic because I love him, I was showing our kids by my inaction and not changing my world and theirs that it was okay. I can't change my husband if he were to chose to drink and not seek help, but I can chose how I react to it. Actions do speak louder than words. His actions and mine.
I'm very sorry you're going this this. ((((hugs))))
Have either of you worked an active recovery program? Regardless of what happens, Alateen or Celebrate Recovery would be good places for your son to get help in dealing with this. It effects all of us in ways we don't see.