cooling off period for starters, venting next then clear your head. what actually happened may never be known. your reaction to what happened is normal and you control what you do about it. you cant control what he does. a tip to the police is a good alternative. if relevant, past behavior, predicts future behavior, he has done it again. its probably so 'normal' to him he will get sloppy about it. dont provide him with an excuse to get out of it. he will eventually hang himself. the cops will investigate him more then once and watch his movements. he has to get the drug from someone. just dont do anything to him you cant 2nd guess him. that would put you on his level and he can lie and fabricate his own witnesses against you. he isnt worth doing time for.