Lisa.. I so get what you're going through. The nurses told us "any time now" every single day for two weeks with my mom. Have you started getting the "suggestions"? Leave a window open, light a candle (loved that one since she had oxygen going), tell her it's ok to leave, etc etc. I snapped one day ... "The window's open, the door's open, there's a battery candle inside, there's a real candle in the hall and she just won't leave cuz she's just to fricking stubborn!" the poor lady kind of backed away quietly.
Her body is shutting down an organ at a time and when it is done it is finished. Wish there was a way to make this part easier for you.. it is indeed exhausting. We're all sending good thoughts.