Aaw Khandie!
That's horrible!
I may be being silly, but I don't understand what "swinging door" means.
If you can't find out who it is, I guess the best thing to do is just carry on as if nothing has happened, making sure you tell everyone you come across about the fantastic time you had at Latitude. Hopefully then it will get back to the person that you weren't around.
Hope you feel better soon