My Mom was diagnosed with terminal cancer when I was 33 and she was only 55. She was all that was left of my family, and man it was tough, we were close. She only lived 3 months past the diagnosis.
I did have the presence of mind to make her funeral arrangements before the fact, after wards I figured I wouldn't be in any shape to, and I was right.
I read a book called "On Death and Dying" by Elizabeth Kubler-Ross which was of some comfort, as it explained what to expect.
Some of my friends are facing this now as we are getting older ourselves. I miss my Mom, but I'm glad it's behind me already.
Sounds like she's living a great life. Hugs to you.
Thanks and God bless us all,
Coyote