Then take this letter and put it in a safe place. You may get to read it to him someday. But if he is not actively working on a recovery plan, he is not ready to hear it. You have already figured that out. Getting it out on paper is like journaling, it helps you release it.
Do what is best for you. We get so caught up in trying to help the A, that we forget to take care of ourselves. I made myself crazy trying to help mine. Didn't think about my heartburn, headaches, insomnia, fatigue, short temper. "Addicted to the Addicted"...that was me.
Focus on your own journey in 2013. That's the only thing you have control over.