hiya desperateintx!
welcome -- glad you found this place!
Maybe try to let it be OK that other people feel differently about this than you do. They are adults and have a right to feel and see things the way they do, just like you do! There's no right or wrong prediction! Only your son has the power to predict what he will do!!
If what's bugging you is you think they will be unsupportive of son's efforts than just focus on that. Say, "I see we have different opinions about how successful Son is going to be but I hope we can all send him the message that we love him and encourage him to use the tools he is learning in rehab."
What kind of "support" do you feel you are missing from them for yourself? Your son is 16 so, yes you've done the right thing, while you still have the power, to get him into a program that might help him. But you need to have no expectations about the outcome. Why? Because you simply cannot predict or know what the outcome will be and you can make yourself cuckoo with anxiety about how you "want" it to turn out. I mean, you can have hope for the best, for sure, but you might want to avoid false expectations.
My brother had what I would have thought a shocking wake-up call to his alcoholism at a very young age....but alas he continues to drink to this day and he is 45. My father drank for the first 15 years of my life and then found recovery in AA. The day he stopped didn't follow one of his worst episodes or hospitalizations, it was just another hungover day...but for him that was the day. None of us could have predicted it would shake down that way....and nothing anyone did up till that point was what got him to stop. He stopped when he was ready to stop....
Have you ever thought about attending AlAnon or Naranon? I found a lot of relief and picked up a lot of tools through those meetings.
Good luck desperate- and stick around and keep posting -- there are many parents on this forum who have walked in your shoes...
peace,
b