MJ or Coke, both illegal drugs. After my exabf was hauled off to prison, at 5am one morning there were several sheriffs and dogs at my front door...they had a search warrent, looking for drugs (long story) anyway, they found pot residue in the garage and clearly explained to me what could happen....like I could lose my house.
You have children, even worse situation, anyone can call CS and report that they have seen drug activity in your home and boom you have the law on your tail and your children are in jeopardy.
Is this really what you want? I doubt it.
If you are done, then be done, if not, just keep letting him come home and let your children pay the price, because they will. I can guarantee that, I was raised in an alcoholics home, I still have the scars to prove it.