Yeah, there's no way to know.
Leave him to it...if you can, maybe find a group of support for yourself like Alanon (It's a 12 Step group for family and friends of addicts/alcoholics.)
I would definitely be worried if there's a possibility he has illegal drugs in the house or car. I wouldn't let him drive with me in the car and I wouldn't drive any vehicle he had access to - in case he has a stash in there. You could be charged along with him for possession.
Some churches have "Celebrate Recovery" too, or family support for family of addicts.
Take care of yourself. As they say in Alanon, "More will be revealed."