SPOILER ALERTApoc said:Not so shocking. Go to www.cosforums.com to read about it. Lots of theorys, with recent chats with JKR, and more.
SPOILERS!!!
It seems that he was severely injured because of the ring, and they agreed to slow down the effect of the curse so severus could fool the DE and LV into thinking he really killed DD. I don't think severus is evil, even in the last fight he kept giving advices to harry ("close your mind, don't speak", etc).
But I obviously could be wrong
/SPOILERS!!!
Yes the advice to Harry was what made me suspicious. There's obviously something behind the whole thing, it would be too easy and dumb to just make Snape officially evil and that's it.