What is your favourite horror book to read? Do you have a most loved character?
there have no such a book  i like all of them  
Have you read The Drowing Girl, there are so many mysterious parts and twist and turns, it is such a good read. 
no  but  i have heard about it . 
Yes it’s a very good read if you get a chance you should read it. It’s a story based on misogyny and murder.
how can i get this  book pdf  file  
You could try onread.com there you can download authors books for free. If not I know they sell it on amazon either hardback or for the kindle app.
i wil try  first at onread.com then i will search  it  in amazon
Also amazon at the moment is running a special promotion if you spend $20 you get $5 for kindle book, so maybe that is also something you can look into. 
it is not a big deal  for that  book