How to deal with book-induced trauma?

So 2 days ago I read this novel. It was boring at first, but became interesting halfway through, but also creeped me out. I didn't see that as a red flag about this author, so yesterday I picked up another of his books. I barely got through 1 chapter before I was crying. I put the book down and went to bed. I cried myself to sleep that night, had a horrible nightmare even though I take medication that prevents that, and woke up feeling horrible. I'm not gonna finish the book. what should I do to stop this from happening again?