Why do I feel betrayed--a friendship question not a dating question

Not sure what you are asking about here?? Was the "friend" you were invited to be with supposed to become a relationship or??

Because you expected someone to act based upon some unspoken criteria you had. your friend had no idea you didnt want hot girls around or that you were trying to limit your contact for any reason. maybe she thought more people would make it more fun or whatever.

To begin with you lack a social IQ and are also socially immature. What does meeting two hot chicks have to do with your Phd.? " I don't like dealing with hot chicks; I'm dedicated right now towards my PhD." ?
That is from a socializing point of view, DUMB!

Now to your question, you expected to have drinks with the young lady and move to the next higher level of making out and see where that leaves you? But being socially immature you could not handle yourself with 3 hot chicks, thus you felt betrayed that she set you up so that she did not have to deal with you one on one! But it was your idea to invite some other class mates to join you for socializing, so you did it to yourself! So your annoyed at yourself and trying to fix the blame elsewhere. Next time take her out as a date.

Harvey7.

If she did indeed invite them, your friend (being female) also may not have thought of the other women as "hot foreign exchange students" instead of simply as fellow classmates. Or, she may have simply run into them and invited them along. Or, maybe someone else did. Or, she or one of the others may have thought that it would be especially hospitable to invite the foreign students to make them feel welcome in another country.

I'm glad that you recognize that your reaction is not rational (it's not like someone invited strangers to join a dinner party at your house -- it was a congenial gathering of friends and classmates in a public setting).

I wonder if you are trying to exert control over your environment because of your worries about being able to succeed in graduate school? If you feel that you won't be able to focus on your studies as you need to if there are any unknowns out there... The truth is, though, that we have very limited control over our anything but ourselves. So, you can't prevent attractive women from crossing your path. You can't prevent people from becoming friends with others. You can't control who gathers in a public place....

You can, though, have some control over your own reactions. Do you just "go with the flow," accept the change in plans, and enjoy the evening (usually the best option)? Do you get angry or hurt, but deal with it? Do you get upset and continue to harbor resentment?

See if you can think a little more deeply about what the real issue is here for you and focus on figuring out how to deal with that (e.g., anxiety about not being in control of your surroundings, past experiences where a friend betrayed you, etc...I don't of course know what the issues might be for you...).

In the future, if you want to limit who participates in such an event, then you may want to organize it yourself and issue the invitations ("I'm organizing a small group to go out for drinks on Friday; would you like to join us?). And, make it clear to your friend here that you're limiting the invitation list...

(Oh; and by the way...lol. Even "hot chicks" can be really nice people and good friends if you give yourself a chance to get to know them. )