Argh! Just kill me now! Talk about ultimate heartbreak, that your best friend ends up being the one who kills you. God I hope that's not true. But the look on Buffy's face in the reflection of Willow's eye says more than just surprise.Actually Willow becoming evil makes sense. Remember she wasn’t too fond of Buffy stealing the money for her own personal gain and after witnessing the rebel slayers, using their slayer abilities for evil. Maybe she believes that performing that spell changed things for the worst and decided to kill off all magic, ending the slayer line. Knowing that Buffy was going to arrive in the future she waited for hundreds of years in order to kill off the last two remaining slayers. Just my opinion.
God, how smoove am I, clicking the karma button out of sheer excitement to convey my agreement, before I've even typed anything out. Har! 😛