Listen, I had a ****ty 2010 for similar reasons. I was great friends with this girl, we started to do coupley stuff, we liked eachother but I obviously was a lot more into her than she was me. I couldn't cope being friends anymore, i kept thinking I had a chance, in the end I just pushed her further and further away and we no longer talk. Almost a year ago to the day one evening she told me how much she liked me, how she wished something had happened etc. We slept together and the next morning she said she just wants to be friends and basically ignored me from then on and just blamed alcohol. I was ****ing devestated.
**** her.
It took me about a year to get over her because I got further and further into my own self wallow and pity. DO NOT MAKE THE SAME MISTAKE. It's sad, it's pathetic and it'll ruin your life.
As the above post says there are a few possibilities about what went on in her head but best to move on. Hang out with the friends you've got, play some sports, go on holiday if you can, do some revision, whatever. Just do something and forget her.
Everyone makes mistakes in life, you may or may not have done in this instance so no point analysing everything that happened piece by piece. Just learn from it.
"You can spend minutes, hours, days, weeks, or even months over-analyzing a situation; trying to put the pieces together, justifying what could've, would've happened... or you can just leave the pieces on the floor and move the **** on."