Until you and wife get on the same page, this is not going to work. You need to tell wife that the two of you need to talk and decide together what you are going to do.
My husband and I were in your shoes not to long ago. It wasn't until we got into serious counseling and really got onto the same page, I started attending alanon and really learned how to detatch, did we get anywhere with difficult child. If the two of you cannot get together on this it will split the two of you up and difficult child will still be running around disrespecting everything you tell him.
A few weeks ago when difficult child was in VT with us he brought along his step work. He went out quad riding with husband and I took a peek at his work. He had a journal with him and I started reading about how he felt each family member, friend etc. contributed to his addiction and when it came to me it was all about how I used to enable him for years and never followed through on any kind of punishment when he did something wrong. At first it really bothered me, but then I realized he was totally right. It also made me realize that the best thing I ever did was stop enabling and detatch. I have faced the facts of how I contributed to his addiction, but I'm o.k. with it because I have changed and I know what I'm doing now is contributing to his staying clean and living a happy healthy life.