I would never ask just one friend to handle nursing me through a recovery. That's a lot of work even at the most minimal. Friends can help in shifts in whatever way is least taxing for them. If I need constant care, put me in a facility.

It should not be only you for long periods of time. I understand wanting to help and realizing how hard the surgery is to recover from, but she also needs to start trying to do something for herself. I had part of my gut removed, was in the hospital for a forced five days, got my ride home and proceeded to do things myself. It wasn't easy, and I fatigued quickly, but I was going to do it, dammit!

I'm kind of surprised you haven't said something to her. Gently, of course. I don't know her life circumstances, but at 83 it may well take her longer to regain her initiative after major surgery. That doesn't mean you have to care for her the entire time. I'm trusting that she's at least saying thank you for all your help as things go along, but even if not, I think it's time to tell her you have to get back to your life, and maybe just check in with her by phone or text to be sure she's okay. Better that than to let it fester until your resentment comes out all in one burst and harms your relationship.

I think if you care about your friend there should be no limit.

I think three days is enough time to spend taking care of her

Takers don't set limits , so givers must.

Thanks for doing that for your friend,Takes a beautiful soul to give so much ,I certainly hope you get your well deserved rest and she can take over for her self or get another friend to replace you,You have lived up to your own expectations ,Hope others do the same for you in the future if required

You are thoughtful

Given the pandemic and uncertainty of the times we live in, I understand her reticence to dip into her stash. But comes a time when she needs to take responsibility for her own well being. You're not a nurse. If she needs nursing care she will have to arrange that.