The Unbecoming of Mara Dyer by Michelle Hodkin (Mara Dyer Trilogy, Book 1)

Mara wakes up in a hospital bed, and the first thing she can really focus on is the yellow roses. No matter what is going on, at least the roses mean her best friend Rachel must be here. Even that is empty, though, they are from Rachel's parents and Rachel is gone...forever. She can't remember what happened or why they were even visiting the asylum that night, but everyone is looking to her for answers.

Instead of answers, all she has is nightmares and hallucinations. PTSD the doctors say, and they want to commit her. She convinces her mother that a move will be enough; moving away from the ghosts of her friends and all the questions she can't answer.

Florida is almost like another punishment. Private school is another circle of hell, and the first thing she does is have an episode and pass out in class. She manages to invoke the ire of one of the most popular girls in school. Luckily, she also manages to make a friend. Jaime shows her the ropes a little, and tries to warn her off the hot British guy, Noah, who keeps teasing her. He couldn't really be flirting...

Besides, she has enough to deal with: she's seeing AND hearing dead people. No matter what happens to you, she knows that is crazy. Even weirder things happen around her: an abusive dog owner drops dead the exact way she pictures it in her mind. And that Noah guy won't leave her alone. She finally agrees to go out with him...and he kind of wins her over. The weird stuff doesn't stop though, and soon it seems like it may be bigger than she ever imagined.

"Things were changing. Sweat pebbled my skin, even though I knew it wasn't possible. It wasn't possible. I was in class at nine this morning, when that bastard died. He had to have died earlier. The coroner, or whoever he was, was wrong. Even he'd said he was just guessing.
  That was it. I imagined my conversation with him. I'd thought he snuck up on me too quietly, but he didn't sneak up on me at all. He was already dead. The whole thing was just another hallucination - par for the course, really, considering my PTSD.
  But still. Today felt...different. Confirmation that I was now crazier than I'd known it was possible for me to be. My mother worked with only the mildly disturbed. I was full on delusional. Abnormal. Psychotic," (Hodkin pg. 103, 2011).

*Library Link*

If you liked this, check out:

The Evolution of Mara Dyer by Michelle Hodkin (Mara Dyer Trilogy, Book 2)
Shatter Me by Tahereh Mafi (Shatter Me, Book 1)
Shadow and Bone by Leigh Bardugo (Shadow and Bone, Book 1)

Hodkin, Mara. (2011). The Unbecoming of Mara Dyer. New York: Simon & Schuster BFYR.