Waysider - K J Sutton

If you go wandering through the dark, you're going to find things you don't like.
When twenty-year-old Cass Ryan is pulled out of the Hudson River, she's officially dead for four minutes. She doesn't know anything about the boy who pushed her in. She doesn't know why she's been hallucinating since coming back. What she does know is that the violent visions feel terrifyingly real, and that her life will never be the same.
Enter The Else & Bellows Institute.
It turns out that Cass's visions aren't visions at all-she's a voyant, and she can see the dead. Spirits and memories are trapped between this world and the next, and because of this dark ability, Cass receives an invitation to one of the most prestigious schools in the country. To ease the burden on her family and gain control over her power, she accepts.
But nothing at the institute is what it seems. There are secrets in the hallways and whispers in the shadows. Her new classes are strange, and some of her classmates are even stranger. There's also an unsolved mystery on campus, a decades-old crime that no one seems to care about solving. No one except the ghost of the girl who was murdered... and Cass. She quickly realizes the real challenge won't be passing her first year as a voyant.
It will be surviving it.