I've been married for almost 31 years now and at this point sister-in-laws are no longer in-laws. They are sisters. My heart aches everyday. We all suffer: her husband, her daughter, her mother and father, her siblings and friends. The grieving is sometimes unbearable.
My only comfort has been her peaceful and deeply spiritual disposition during much of our interactions. I don't know how to describe it but it is oddly reassuring. It is as if I am getting a small glimpse of the rest she will experience once her time on earth is complete.
My brother-in-law, her husband, sent us all this very good article, which is attached, on family upheaval during terminal illness. It is really very good at outlining what families go through when a loved one is diagnosed with a terminal illness. I recommend it to anyone wishing to understand this process. I left the highlights my brother-in-law noted.