Oh man Pat, I'm sitting here trying not to be morbidly fascinated with your situation, because I know that must be super sucky. Like... I don't want to be one of those losers who is all "hey I totally know how you feel, you know this one time...". But basically you keep seriously reminding me of my senior year of high school. I had a super serious girlfriend at another school, and over the course of the year I basically developed a circle of girls who I would just hang out with and flirt with all day. And I am so not proud of this, even though at the time I was too caught up in everything to care. The fact that you already feel bad about it is a good thing. It means that while you are conflicted, you are still trying to think with your big head. My situation eventually led to me cheating on my (now almost-fiancee) girlfriend. Much too long after the fact, I told her the whole story, and much crying and drama was to be had by all. But the fact is, this show is not going to last forever. It is going to end, and you are going to go back home, and you are going to see the girl who has been missing you this whole time, and things are going to be awesome. And... face it, hot, flirty girls are a terrible thing to do to a man, and there will be moments when you can't help yourself. You are straining at an inhuman level here, and I, for one, am proud of you. I really hope you don't let this stuff go too far before you can see your girl again, and be reminded why it was worth it.
tl;dr: This one time in high school I was a total dick, and I would like you to learn from my stupidity.