It's hard for me to read horror with any kind of distance, especially psychological horror. Flickering between the words that should sound insane to me is the familiar itch of maybe that thought is true. 
Abby isn't questioning her thoughts, she isn't taking a step back to review. She's deep within herself and doesn't understand how to be out. It feels like a front row seat to thought patterns I am all too familiar with. To me the horror is how easily the insanity feels possible for me to reach. For that reason, I am not the correct audience for this book. 
My main issue is that I wasn't sure if diagnosing Laura with Borderline Personality Disorder did much for the story, I can't work out if that was there to hint to the reader that Abby was experiencing similar thoughts and patterns. If not it felt unnecessary and unhelpful to people with BPD, perpetuating the narrative that BPD is incurable and inherently evil. 
The story itself was intense and well written, I didn't spend much time grasped by beautiful sentences but I did have a lot of squeamish moments at the sheer quantity of bodily fluids throughout.