How should i dump my friend?

I have had a friend, whos in my cl for 2 years now. We didnt use to be that close, it was more just a happy coincidence that we went to school together. Anyways we took the bus together and hung out a bit along with other clmates at each others houses. We had a good time back in the early days, but after a while she started "demanding" more from me. It has been like this for this entire year and i culminated a couple of months ago with a huge fight. I have since "made peace" with her, but its only for the sake of school (me having to see her). I have since realised a few things.. She is a very insecure person who displays this by acting like a *****, she only talks about herself along with a bunch of crap about other people, and she is overall very demanding (i feel like she never leaves me alone and has bad mood swings if you dont act like she wants you too) We graduate in 2 weeks and after that i feel like i never want to see this person again. How do i break things off? She will not understand or accept this and probably try to har me on facebook or other websites. She can be a very cruel person (despite me knowing this is due to insecurity i still hurt from it) In a way, i dont even feel like explaining anything to her about how i perceive her, i really dont even care about her that much.