Y'all can laugh at me for this, but I just googled "meaning of whole world turned upside down" Here is what I got:
"turn someone's life/world upside down
to change someone's life completely, often in a way that is shocking or upsetting"
http://www.macmillandictionary.com/us/dictionary/american/upside-down
Questions about the evening:
1. Why did she leave the party so quickly? She was there less than an hour
2. Where was she during the time prior to McGrady's?
In my opinion, this didn't have to do with a romantic interest. It was rumored that she wasn't seeing anyone and she wasn't even talking to anymore, and Hannah strikes me as the type that cares more about school, sports, and being with her girlfriends than putting her emotions into a boy. JMO. But it is possible that Longo, having access to her friends and possibly text messages, is alluding to something gone terribly wrong? My instincts tell me that at the first party, her drink was spiked with something...doesn't have to be a rape drug, but something....and she tried to run off the high. As in, make it go away. Then, I believe she was given a date rape drug at Tempo.