Danman has given advise on how he deals with his situation as he wants to stop. Does your husband want to? It is a difficult situation because he may think he hasn’t got a problem. We cannot make them stop whatever we say, do or threaten. They need to do it themselves.
I too was looking everywhere. I still find the dreaded stuff now and other drugs around the place. It will drive you mad in the end this detective work. There is no right time to approach him if he is not ready.