I'm so sorry. I can see the ultimate trap she has you in (or rather her disease has you both in) and the incredible guilt that goes along with whatever choice you make.
I don't have any good advice, mostly because there isn't any. Knee jerk reactions say save yourself, but at what cost? Making the decision to walk away might be the smart one, but can a person really do it?
What about taking control of her and her affairs based on her diagnosis of Wernike-Korsakoff Syndrome? If you have total control over her finances, her medical stuff, etc., I don't know if you would be able to make any more progress than you are right now, but at a minimum, you could "force" care on her at least relieving you of the forcing her to eat, going over and checking on her.
Perhaps another option would be just setting SOME boundaries to start - ones that you can live with. Like - you will drop groceries off 2 twice a week but not feed her, or you will check on her physically on Tues and Fridays for your own piece of mind, but that is it. Maybe once you feel like YOU have some control over this, you will be in a better place to make the decisions you need to make for yourself.
You know this isn't your fault - say that daily, write it on stickies on your car, get a therapist to help you remember it, tattoo it on your arm if you need to . . .