First let me say I'm sorry.
As one of the token females in the group, I say move on. If she wanted to make it work, she would. Not sure if there was discussion before hand that she was going to grad school in a different city and what would happen. You sound like the good guy to fall back on. Never, ever, be someone's safety net.
Take a deep breath and move on! I would not answer her texts. Don't let her bait you nor play with your head. This is why I hate most women. I always got along better with the guys.