More detail into my synopsis

Basically the main character is a girl of about 18 who wants to take her revenge on these three girls who are making her life a complete misery and nightmare. She is a very reserved character who doesnt like to speak much but only if she really has to, she spends alot of time alone and doing unusual activities, she lives with her mother who doesnt understand her at all and wants her to become more outgoing. She doesn't intend on killing the first girl as she just wanted to warn her off, however she then realises that since one of the girls have now gone that the others haven't quite picked on her so much and the police don't suspect her initially because they saw her as the original victim. It's only when she murders the next girl; because of a comment that the girl makes that accuses her of being a suspect, that people become more suspicious and wary, the main character then becomes crazed with guilt yet she is not seen as sinister so its for the audience to decide whether she is the actual "bad person". It is going to end with the main character taking her own life as a result of having no friends, being racked with guilt and no support from her mother.