There is never anything wrong with trying to save your sanity and your health. You have tried and tried, and it has got you no where.
Please take what you need and leave the rest - from your meetings. Many recovering addicts that I have met have told me - the best thing for them was when there family cut them off and cut them out. Of course, there is still no guarantees this will help your son but it will help you and it has helped many addicts.
You are not giving up, you just know you are powerless and the only way - is to now give him to God.
My prayers are with you and your son.