I would like to thank you for reading through and appreciating my work, it means a lot.
I would go ahead to clarify you on the things you asked, I'm so sorry, i really need to work on clarity on my work, the subsequent ones would be better.Hi @agmoore,

it is entirely fiction, they are all just characters in my head, so yeah, the tragic end is in my head too.

the ending wasn't so clear i didn't realize because my head understood the ending i meant, i guess that's because I'm the one who wrote it.
The end as i thought would portray is that, Arianna, the elder sister, gave Yuri her lungs as getting a donor wasn't forthcoming so in my story she is dead. Then as to why the younger sister didn't know about the book it was because Arianna wrote the book while Yuri was in a coma for 65days. so Yuri could only find out about the book after her sisters passing.
So Arianna is the writer of the book and Yuri was the one who read the book as a gift from her sister after she had been resuscitated.

I hope this brought enough clarity. thank you.