It's not your calling to be invaded, chewed up, and spit out again to make this guy evolve into a better person. Someone who wants to make someone else a reason for his recovery will make that same person the reason for his relapse. Let the big boy make his own choices, and take the consequences too---and ignore the crazy-making quacking.
And don't be angry at yourself---learning to be and stay no contact is a skill, and takes time to learn, considering how most of us here were focusing all our time and energy toward the addict in our lives. Not an easy task to turn that focus and energy on ourselves, where it belongs! But I find it gets easier every day---and the payoff of peacefulness and sanity is so worth it! Personally, I no longer think I'm going to develop health problems from constant stress, now that my STBXAH is out of the picture!