I'm so sorry that you are going through this. I understand the fear of answering the call. It is horrible to wait, but then when the time comes you don't know if you can handle the possibility of bad news.
I don't know if this is the kind of thing you would practice (some people might think it's weird), but it was recently given to me to help me through the waiting game. It is a positive affirmation and can help lower your anxiety a little:
Breathing in I calm my body.
With each breath I choose to inhale poise and strength.
I exhale any thought that does not serve me.
I know I am supported.