If you have to ask yourself what you should do, that's a sign that you aren't comfortable with this arrangement. Pay attention to that and let this be one that got away...
A relationship isn't meant for 1 person to be alone and another to be going out and having sex. It's supposed to be 2 people committing to each other. I'd say leave her and find someone who actually cares about how you feel
Believe it or not, loving someone isn't a good enough reason to stay with them. No matter what, you have to love yourself more than you love the other person. If you don't love yourself enough to insist that you be treated well in a relationship, then there's a problem, and you're the one that's going to pay the price.
There WILL be another girl... many other girls... and you shouldn't accept treatment you think is unfair from any of them either.
Yeah you can find someone better. If she just wants a relationship with sex than she's not worth it, and if she doesn't accept that you cant, she's not worth it. You could just tell her that for now until youre older, you guys could take a break from each other. But make sure she wants more things in a relationship than that
I don't really know about relationships and cheating, but I will tell you this...DUMP THE CHICA!! She is not worthy to have a guy like you. even though I do not know you.