Another story that is similar to what you are after is ‘Bridge to Terabithia’ by Katherine Paterson. In this epic tale of two children It is the death of one that is the climax. If a day by day is what you are after I would recommend this book as a reference material. I read it when I was a child and it still sticks to my mind. You will find the dynamic between characters is what pulls the reader through the book.