Hello there this is a great place for support and insight. I feel very much for you, the addict in my life was my husband, I hope I never know the pain that having an addicted child must bring.
Re the judgements of others, there are those who may think unkindly of your actions, I've been guilty of it in the past, but it really is none of their business, and if you need a reply to this sort of interfering:
I will be told that I have deserted him and he needs what ever help I can give him.
you could point out that you have been doing this for 22 years of his adult life without it making a difference, and with it risking your health and relationships with others you care about you have decided to allow him the dignity of making his own choices in life however much that pains you.
that would have stopped me in my tracks and I've been a world-class know it all when it comes to other people's lives.
((Hugs)), none of this is what we dreamed, or easy, I can hear your exhaustion and pain, and I wish you some peace. Finding others in the same situation helped me find some peace, I hope it does for you too.