I would like to comment regarding siblings caring for aging parents. I went through this last year when my dad was diagnosed with a glioblastoma brain tumor. He took the treatment but declined in health and passed away within three months of diagnosis last July.
As for working through everything, when the diagnosis came down my only sibling - a sister - read me the riot act on the phone laying the guilt trip on me. This major argument upset me beyond belief. I live in one state and she lives near our parents in another state.
Since I am not flush with funds, I had to meter out my trips to their location, but went during critical times. When our dad was in his last days, she opted not to participate in his daily care so I was the one who took on giving him his meds, diapering him, emptying the catheter, etc. in hospice care and did it as well as I could for a lay person.
I was surprised to find that my sister and I got through most of the care giving without incident, but I also believe that was at least partially due to the fact that I decided to keep my thoughts to myself regarding her behavior.
I was able to say good bye to my dad on one of my trips, but was not there when he passed away. My husband and I, of course, returned for the funeral.
I will say this. Anyone in this situation will have to choose to put their feelings aside in favor of caring for the elderly parent as that is what is really important. I believe I handled things in the correct way and have no regrets for how things turned out.