After being bullied because of her autism, a misunderstood college student joins a secret sorority group of girls only to find out she has a kill a fellow student.

1) She kills a fellow student after a prank gone wrong.
2) Her autism is stopping her because she is afraid of being bullied. It is realistic.

The only movie that comes to my mind when I hear about a protagonist who MUST kill someone against their will is "The Killing of a Chinese Bookie" by John Cassavetes, where the killing was to balance a huge gambling dept to the mafia.

What are the stakes in your story? She must kill a fellow student or what? What's stopping her from reporting the sorority as a crime organisation? Her autism? Is this realistic?