Oh can I relate to the "drinking" stuff. My H is like your W, when he stops off for a couple he's lost to me and to time. The majority of time he has more than a few, he drinks until he's drunk or "full" as he likes to refer to it. My H has been drinking heavily about the last year and half, meaning at least once a week. And he drinks till he's drunk!
For some reason I pretty much "feel" when he's going to stop for a few or if the urge is going to hit him to stop for a few. Must be an intuition thing. For the most part, he doesn't call to tell me he's stopping either. He works construction and drinking tends to be entertainment for the majority of these guys.
I think deep down he knows he has a problem, I've mentioned it to him before. His mother is an alcoholic, also. My H is also dealing with MLC and a lot of other issues or should I say avoiding the fact that he's getting older!
When he does get like this I detach from him, it's about him, not me. I don't know if there's a lot that can be done by us, I think the drinker has to hit rock bottom or have some kind of "bomb" in order for them to see that they have a drinking problem.
I've done the waiting thing, too. I don't anymore. Maybe you should pull a 180 on her, don't be waiting there for her when she decides to stop off and not show up at home, just a thought.
Does your W drive while she's drunk? This is what scares me the most, not so much that my H will run off the road and hit tree or fall asleep BUT that some innocent person will be hurt or killed!!