24 years and surviving

I'm 24 years old and I was diagnosed with Hodgkins when I was 19years old. I survived my Grandad, Grandma and 2 close friends. My one friend and I were diagnosed around the same time. She had lung cancer, beat it and then a year later it came back and spread to her brain. Just as I was getting better she was facing being sick again. Her family and friends were devestated. She was the glue that held the family together. She used to talk to me about what she thought it was like to die. She said she hated it that people alienated her or treated her like a child. She said she was ready to die and at peace with that and wished that her family would be too. Our visits were usually once a week and she would often tell me that I was the only person she didn't need to be strong for and could talk about her true feelings with. Why did I get to live and not her?