Welcome to SR Rhode, I see lots of folks have chimed in and I'm once again overwhelmed by this caring community.
I was once in your shoes and know exactly how you feel. It's a powerless and frustrating feeling but there are answers. Education about addiction and getting support is the key. I followed the 10 Ways Family Members Can Help steps to the letter as though my own sanity depended on it.
I remember when I was in your same situation, my MIL and I were planning an intervention with professional help. Just several days prior to the planned intervention date Mel decided on her own to check into rehab. I'm betting your wife is well aware that she's in big trouble.
As others have mentioned, when I was confused or unsure of what to do I always put my childrens priorities first, and that helped me make some tough decisions.