So sorry to hear that - to beat the breast cancer but have the very thing that could make you better take your friend from her family and from you and her other friends.
I'm really sorry to hear about your friend. Cancer is such a terrible thing and it takes to many of our loved ones away from us. My prayers to all of you.
I am so very sorry and I can relate. There will never be anything that I can say to ease your pain, but please know that there are others who understand. It never gets easier, does it.