Dear JMF, You are hurting yourself & hurting your son also. I don't know how old your son is but mine will be 42 in Sept & cuz my parents never could say no his addiction has been going on for 20yrs!!!
Do you want your son's addiction to continue? For you son's sake and for yours say No. It is a complete sentence.
Believe me it will be harder seeing your son destroy his life than it would be just saying no. Be strong for him if not for yourself.