Crushed,
You have played a role in this. It sounds like you looked the other way for years on her drinking. What did you look the other way for years on your marriage for her to be lonely enough to have an EA (at the least) with the boss? Is the drinking a response to depression or a personality disorder? Does she have a MD that she could visit to discuss a plan to dry out and assess what is truly going on?
This might tick you off to look at your own role in this relationship - but honestly that is all you can 100% impact if you choose to change. The ostrich approach eventually you choke on sand... Get the grit out of your eyes and run around a bit to clear your lungs.
I wish you all the best.