Death and Sickness

17 years old some at this age may have experienced death or a fatally ill relative. I however have not everyone around me is healthy the only close person that has died is a close family friend and I was five at the time. Life went on after the person died. Whenever a conversation about death comes up i usually say "yeah, idk how i'd react idk if I would react, I'll probably just be awkward, sad, and then eventually move on" it hasn't been real for me. For the first time ever yesterday one of my closest friends who I've known for 4+ years a person who is more than a friend but like a sister to me. She's someone who is always there for me at anytime. Even with over controlling parents she is there and has been there for the big parts of my life. She has been diagnosed with ovarian cancer and I broke down I don't even know the stage or severity only that it's been there since I've met her. For me I felt immune to death and sickness especially  because no one near me died or has been fatally ill it always seemed distant something that'll happen way later in life. When she told me time had stopped everything in sight started fading into a blur all the memories and time spent together started flashing by, then came the thoughts what if her surgery doesn't go well, what if they can't get it all, then what if I lose her. I broke down in tears yet she hasn't cried about it. This is someone I grew up with, someone I plan to grow old with, and someone who I see in my future I don't want to lose her she doesn't deserve this she hasn't even gotten a drivers permit, a job, a high school diploma, a degree, and so much more. I just don't know how to react to it all, honestly the only echoing thought I can hear is I don't want to lose her.