Frank, I'm sorry she is using and sorry you are bound to be hurt either way...walking away or staying for more of the same. There is no pain-free way out of this, for you or for her.
You deserve better than this, we all do. As painful as they are, we have choices and sometimes letting go is the only healthy choice.
My prayers go out for both of you. How sad addiction is to take those we love.
Hugs