My thoughts and prayers go out to your friend, her family, you and your family. Just be there for her, listen to her when she needs to talk and have lots and lots of hugs ready.
I am so sorry to hear about your friend's breast cancer. I will certainly say a prayer for both her and yourself and your DH that you can support her in the ways that are best for her.
I second that - I have a dear friend who was diagnosed with ovarian cancer TEN years ago. It was stage III B which is VERY bad - had spread to multiple places. She is a walking miracle. Except for the fact that she gets chemo 12 hours a day you would never know it - because she does SO much for others. Her attitude is such an inspiration.