Try to think good healing thoughts as much possible even when it doesn't seem like you can anymore. Enjoy your sister and the time spent with her and don't dwell on what is happening unless she wants to talk about it. None of us know what is going to take us out which is why everyday should be spent like it is our last. And don't avoid her and make sure other people don't. I have had experience with friends and family saying "Oh they are going through so much I don't want to bug them" then the one who is sick is wondering where everyone is (seriously)
. This is the time when they should be all around her giving her love and support.
I will say a healing prayer and include her in my thoughts today. I am on a job on an island so I will take a moment and look out over the ocean and send healing thoughts her way!(((((hugs))))) Take deep breaths!