I know how rough that can be since she's always around you, but there are ways to semi-avoid her which will help make the process easier.
So first, don't contact her whatsoever unless you have to. You can talk when you're in person but no phone conversations, don't text each other, no messaging each other on Facebook or tweeting on Twitter or anything like that. If she calls you, texts you, messages you, or whatever, then ignore her. If she confronts you about it, be like "I was busy, sorry about that."
Second of all, find other people to hang out with. When she is around, don't just stick around with her. Find other people to be with. Pretend that you don't see her or that she's not there if she tries to bug you. When she's trying to make you jealous, keep in mind that she's just putting on an act to get a reaction from you. So if you don't react to it, she has no show to put on and sooner or later she'll get the idea. Every once in a while, do acknowledge her existence but be aloof about it. Don't try to get into super flirting mode with her. Just relax and talk to her like she's any other girl. Try not to make it awkward and proceed as you would normally. I know this may be hard but with a little self control and practice, you'll get it.
Finally, if nothing ever works and she has pushed you over the edge, go and confront her about it. Tell her that you don't like her doing the following actions. She'll probably either tone it down or get pissed off. Either way, it'll be easier for you to get over her. If she tones it down, you won't have to think about her so often. If she gets pissed off, then you probably might end up disliking each other (not the best idea but you do get over her).
These are the steps I take with an annoying crush. It works for me so I hope it will work for you. I'm not saying that it will, but there is a chance that it might. Just learn to control yourself, your emotions, and your desires. Best of luck!
