I am very sorry to hear of the loss of your dear friend. It must have been such a shock to hear that she had passed when you were hoping to see her again. Also to have shared a rare cancer (I imagine) would have been a special and unique bond that you may have not experienced with many others. That makes the loss even more unique.
Reading your post has been helpful to me because I have felt alone in the grief I experience from the death of friends' children from last summer. My baby was in the PICU all last summer, so we became close with four families whose children were also in intensive care…some from rare autoimmune disease, some from cancer, some from tragic accidents. Although we were strangers at the beginning of the summer, those intense weeks of living together in incredibly emotional life or death for our children situations brought us instantly close. We shared our deepest fears and most terrifying moments. Since then, every one of the children has passed away. Some of the ways I found out about the children's passing was traumatic. I have kept in touch with some of the parents, but others, in the overwhelming circumstances, we didn't think to exchange contact info. So I have no way of getting in touch with them. It has left me feeling isolated in my grief with a lot of pain for the families. I think of them often, planted trees in their honor, but still feel there is a lot missing in my being able to process the trauma and loss. I would love to hear how others have dealt with this type of grief as well.