Hey Sam,
Man I'm sorry you're dealing with this mess! I don't have much to offer other than my support and prayers..
Alcohol and Xanax is a deadly combination! Personally I'd call her doctor and let them know what's going on. I know the intervention didn't work the first time. I'd try another avenue and get her into a rehab facility..
Please keep posting here, as mentioned above look up your local Al Anon group, they can support you locally and are wonderful people!!
Wishing you the best!!!