When I first read the OP I was going to immediately launch into a diatribe about not judging folk so quickly, but then I sat back and thought about my own self.
Social skills have never come naturally to me. I used to have extreme difficulty opening up to people I didn't know. I find social situations where there's a lot of people I don't know to be really hard to take.
It's not something that used to bother me a huge amount, because I always had my mates and my friends.
So I can well understand how when you were put in a very new social situation that you didn't know how to handle you went straight into flight reaction.
I had to overcome my social phobias when I moved to a new city and didn't know anyone. It forced me to get out and just try to strike up a conversation with randoms. I've come an extremely long way. You just develop an intuition after a while, you just learn to go with the flow and detect when the vibe is bad.
I would honestly suggest going back packing. And I mean proper back packing. Don't use dad's credit card, pack light, rough it, and travel through some back water country on a shitty motor bike. You really learn to just take people as they are, and man, you will meet some incredible people when you start to be a lil less guarded.
Not to sound condescending, but you just sound like you need a little more life experience and exposure to the real world. Great news is you're still young and have plenty of time to learn about the world around you and yourself as well
Take Rat's advise on trying to salvage the situation.