I can understand your wanting to support your son especially if he is involved in counseling. It is best for people to remove themselves from people/places/things that remind them of drugs, or trigger them to use.
Are there specific reasons why your husband does not want him in your home? Were there problems in the past?
The person that brought me here is my husband, so I know its a different situation. But one thing that helped me was private counseling of my own. I was able to learn about addiction, learn healthy ways to support my husbands recovery, and had someone to talk to about my own feelings, worries, etc. Is it possible your husband might join you in something like this? Maybe it would help get everyone on the same page.