future captain
I know exactly how you feel. I can't get it off my mind. So much effort and time (and money!) went in, all to fall at the final hurdle and recieve a generic rejection email with no feedback. It distracted me from my studies and still does. And as you say, if the smallest thing went different on the day I'd be on top of the world right now. Life's all about margins.
It's going to be hard to get over it. As tough as it is we've just got to pick ourselves up and hope for another opportunity!