I wasn't completley shocked because deep down I always knew it was either nick, Melissa or Diana because Faye was to obvious.
During the whole episode I was like its Diana, no! It's Melissa lol Everytime Melissa went near the crystal I was like this is it but when she touched it I was like Damn! So it has to be Diana.
When it was revealed I still felt the emotion which means they did it right! :) I'm happy, this will bring an interesting dynamic to the show. Faye's anger, Charles and Diana, and most importantly Cassie and Diana. Oh and Diana's good girl gone bad path ;)