Clues

  1. The murderer was a writer. 
  2. The woman was a character from the book. 
  3. In the woman's life, a family tragedy happened. 
  4. The author was shot by a mentally disordered fan of the book. 

Solution

There was a novelist who had been writing a saga for 18 years, one book a year. Having a worldwide recognition, he managed to create quite a big fan base. After such a long time, he got tired of this novel and decided to finally drop this work, so he came up with a gruesome ending for the main character. The finale included the protagonist's parents' death and her boyfriend cheating on her, which led to the woman's suicide. When the book was published, one of the most dedicated and also mentally disordered female fan sought revenge on the man who killed her beloved character. She shot the author in his house with a stolen gun.