GoodKarma,
Your reaction to him is normal behavior in the abnormal situation of being a friend or loved one of an addict. There is nothing in your behavior to feel shame or guilt for.....it's the usual outcome when addiction sucks us into obsession about what the addict is doing. This happens to each and every one of us and this is what we try to recover from. Some here have had more time to recover and some are new at it and it often takes a few years to really unlearn the patterns addictive relationship sets into place. No one here is better than anyone else and we are all subject to codependent relapse.
I understand the concern...the wanting to know if he's just a user or also a dealer (lots of users are dealers as you know). Certainly if you are afraid for his possible arrest, the punishment for one is much more severe than for the other, and I understand your concern.
But I'm so sorry to tell you that even knowing the truth would not help you nor him. If he is using illegal drugs, I would be careful about what he might hide in your car or your home. If he's dealing, I think I'd rather not know at all so I would not be an accessory.
But I do have to say that if I were married to someone I suspected might be a drug dealer, I would want to know as much as I could of any kind of serious criminal activity which would create severe legal problems for me.
But if he is not your husband.....well, God withholds information from us for a purpose. There is a larger story at work, I believe, which is playing itself out.
So...if he's just a friend and you have no legal need to know if drug dealing is taking place in your home, then please find a way to disconnect from his personal pursuits. It pulls you away from your center and before long, you bounce from one emotion to another, and your thinking and behavior becomes erratic.
Good luck. Stay safe.