This was, without a doubt, one of the most horrific yet gripping books I've ever read. The writing was excellent, and the storytelling tight, but by all that is holy it was harrowing thing to read. There were periods where I had to put the book down, and others where I felt physically sick, but in the end it was... a good book. 
 For anyone reading it, I would suggest maybe taking breaks and reading something lighter as opposed to marathoning through it like I did. It might help.