One of the best, hardest things I learned in a family recovery program was "No is a complete sentence." You have the right to say "No" without needing to justify, rationalize, explain. Your son will have his reaction....and that's okay too. Let him have his reaction. Let him kick, scream, complain, etc. His reaction does not require a response from you. Say "No" consistently and he will finally get the message. Give him the dignity as an adult to figure out his own way....stop rescuing. He has to learn to meet life on life's terms. From what you've described, he may be sober but I don't think he's found true recovery yet. If he works the steps honestly, he will learn to live differently. But as long as no one can say "No" to him, there is no motivation for change.
It's not easy.....but it works.