I am a caregiver in a memory care facility so i have delt with quite a few hospice cases. i understand your pain and confusiion they r very normal emotions to be feeling. one possible reason your aunt may have said she was going to be busy was because she does not want to "burdon" you with seeing her pass away. i see this alot even in people with alzheimers. they dont want theirbloved ones to suffer.
i believe the difference between this situation and a depressed persons situation is that depression in and of itself wont cause death, acting on the thoughts does, kidney failure heart problems and such are quite different, i have been told by dialysis patients that it is painful and unpleasant. with hospice she will have mediicne that will calm the pain.I that it is good that she is mentally able to make that conscous desicion,the people i deal with arent and it is sad. i have an aunt who has very low funtioning kidneys and has refused dialysis as she feel when it is her time it is her time. she has had a do not recesatate order in place for a long time. if you feel i can help u in anyway feel free to private message me.