Hi Shannon,
I sympathise with your jealousy and it's normal. You've been through a horrific experience that no-one and I mean no-one should have to go through and of course that is going to make you feel much more weary. Your eyes have been opened to a big bad world that most people can't even imagine.
It sounds as though you are putting a lot of blame on yourself for being a normal teenager. As I said, who didn't drink? And flirting is an important part of growing up, I still do it now, there's nothing wrong with a bit of flirting and it definately isn't an invitation for sex or rape.
Muzik is right, it was premeditated, which means that they probably would have done it anyway, don't blame yourself. Youth is full of naivity, everyone has to grow up and you were robbed of that so early.
In normal circumstances, you lose that naivity as you grow into an adult and take on more responsibility, having serious relationships, learning to drive, getting your own place and eventually marraige and children.
You've had to grow up before your time and you envy those who haven't. But know you know how bad the world can be and because of that, you can learn to be much more vigilant.