timetogo;
again my heart goes out to you. "using" or not while actually at work and liability is a question for lawyers to answer. i would take an educated guess and say that active chemical addiction even without actually using on the job can and does blunt cognitive skills.
you and only you can decide what u want to do. you might want to know the legal ramification of possible courses, and for this, a lawyer is best qualified.
sounds like you will have no problem showing he is alcoholic. how did you make ends meet when he was in prison?