I am happy to report that so far things are going better here than I expected. In the first place, I'm feeling pretty calm about my mother's condition. She's resting comfortably in the hospital awaiting surgery this afternoon. The doctors and nurses are being good about controlling her pain (i.e., they are listening to me and accepting my advice :) ) I don't have to get aggravated about her care. What happens after the surgery remains to be seen.
My sister and I have been able to peacefully discuss Mom's care and condition and other than that we stay out of each other's way. She is voluntarily smoking outside and not leaving her cigarettes laying around so that's a help to me.
So thus far things are going better than I expected. The next 2 or 3 days will be critical, however. Please keep praying that things work out for the best for my mother (whatever that means).