Hi,
Jealousy is a symptom of not knowing your own worth. In other words, you can only be jealous if you believe someone else is or might be more worthy of someone or something than you are.
That's only true as long as you make it true, and no one can really stop you from making it true except you.
What's worse from her point of view, however, is that being jealous implies that you assume she's going to betray you with a male friend. In other words, you doubt her love for you, so it cannot possibly be real (and neither, really, can yours for her be real).
Not a pretty picture, is it?
This probably isn't what you wanted to read, and you're welcome to reject it -- this is, after all, just my opinion -- but I suggest you consider it and see if there's even a bit of truth to what I've said.
You want to get over this jealousy thing. In order to do that, you have to find your own worth. But that usually isn't an easy thing for someone who is jealous to do! To make things more interesting, you just might lose the girl, anyway. Once you really love yourself, you just might realize that she really isn't the girl for you after all.
Or maybe you'll realize that she really is.
Or maybe she will cheat on you.
Or maybe she'll cheat on you and she's really the girl for you and you'll forgive her.
Or... so many possibilities, so little time to write them all down...
But, either way, once you've learned to value yourself, you won't be worried about whether or not someone loves you, or pretends to love you, or is going to cheat on you. You'll just know, and you'll be able to spot the cheaters and the pretenders a mile away. And you'll also know that you don't want to spend your time with someone who doesn't really love you, and you won't be afraid of letting go of a wrong relationship.
The perfect mate will appear for you the moment you're ready to let yourself have her -- the moment you know your own worth.
Good luck!
=-John-=
P.S. Knowing your own worth doesn't mean that you stop recognizing the value of others.