It is happening. You can phase it out of your world but that would also exclude her from your reality. Now is your chance to give back part of what you received from her. You can postphone your breakdown for as long as she needs you! Believe me; you can! I've been there and could postphone my breakdown for almost a year...
My brother-in-law was diagnosed with non-hodgkins lymphoma, a form of cancer that gets 50% of its victims.
The treatments available now are wholly different from 5 years ago and there is hope. It is by no means a decided thing, so try to keep your spirits up and support your friend in whatever way you can.
A few years ago, one of my good friends at collage was taken into hospital with what we though was pneumonia. As a matter of course with such things, a chest X-ray is standard procedure. As it happens, it was my mum who did his x-ray, and subsequently discovered the large cancerous mass on his chest.
And the worst part? She knew for 2 weeks, and couldn't tell me because of patient-staff confidentiality. She couldn't even tell my friend at the time. Instead, he had to wait for the doctor to check the film before telling him.
Incidently, a year later, he was given the all clear. It was expected that he would require further treatment after the chemotherapy, but they tried a new combination of drugs and it worked, completely destroying the cancer. Although it is my belief that it was his positive attitude towards the whole thing that helped most.
I know it's hard, but try not to get too upset, especially in front of your friend. Put on a strong face, try to have a laugh and a joke, and most of all, have faith and believe that your friend will recover.
Hey Kleio (I still want to call you Cliolune. Can old "friends" call you that?). I don't suppose there's that much for us to say except that you have our support and sympathies. I recently lost a dear colleague who was something of a mentor, and it's obviously very hard. Continue being a good friend. That's the most you can do.