Am I getting mad at her for the wrong reason?

Wow!!!

these are all very serious warning signs. Let me tell you, when your young you want and think everything will be perfect someday and this will last forever….not! you will be off to college before you know it and the field is WIDE OPEN…….there will be many girls that would love to get to know you! Girls who are looking for someone who they can trust and know they wont be going off with some other girl to go hook up…..in my book once there is any dishonesty in a relationship….there is a scar. You may pretend there is not, but its there and there is no guarantee this person is going to remain faithful the next time temptations is there….like the saying goes… once a cheater, always a cheater. Your current gf is only 16 shes not ready to have just one guy and shes proved that before…… you are almost 18 and you need to experience other girls also. Then maybe later….much later if your paths cross again you may find you were a good match and you can try again on a much more mature playing field. Im not far from your age, and i can tell you my first bf who i thought was the one has changed so much i know now he was never meant to be….funny how things work out. But you are both young….you will change….she has already shown a sign of temptation….i think its time to make a break…. keep it clean, you can remain friends but its time for each of you to really discover who each of you really are…..especially you on your way to college, you need to go as a single man so you are free to develop yourself and not to be worried about what she is doing or not doing…. OK!

Good luck…..its all good.