Is OM back off the wagon? Or was he holding back tears/emotions?
I would stay away from him. Tell him straight out how you feel.
I had a BF that I loved very much who did drugs. I finally told him to leave me alone, I was with my (then) fiance. He killed himself with heroin. I will (partially) never get over that. It's hard, but I don't feel like it could have been done any other way. I let him loose, he had to move on or give up.