Well it seems you married for the wrong reason, firstly, you married too young and secondly it was a marriage of convenience, his convenience!
I would never let my stepdaughter (yes, I am also a stepdad) marry someone who’s being in trouble for drugs just so the law will go easier on him, if he can’t help himself and keep away from him, I’m sure he must’ve given you grief all though your marriage.
Also I wouldn’t keep things hidden from the mother either, times like this both parents have the right to know whats happening to there daughter.
So many times we learn the hard way.