When I was in college and confused that boys didn't love me, I would call my dad (yes my dad), and he would give me very sound advice. One of the best was this: Your problem is-you meet a boy, verbally vomit all over him, and then he's too busy cleaning it up to get to know you.
My dad came up with 'verbal vomit' BEFORE Mean Girls. In fact when I first saw Mean Girls I was sure that I had told too many of my friends about my verbal vomit, and that it MUST have gotten back to Hollywood.
But the truth is, your ideas are not your own. Someone else is having or has had your idea, and it will probably be published if it hasn't been already. I was struggling with an idea in my novel that I thought was pretty special. Today Wikipedia showed me that there were three other authors with my idea. After the initial shock of NOT feeling so special anymore, I decided it might be a good thing. I thought this angle on my novel would not work, but apparently it already has.
And in the end, the beauty of it not being my own is that I can make it my own.