Darkest moments in Kingdom Hearts?

I personally think that the moment in KH2 after Sora sees Saix in Hollow Bastion, after Maleficient dies from the nobodies (Sora: How am I supposed to fight without the Keyblade?) was kinda sad, it made me think of how Sora is feeling, his stress. But mostly I'll agree with everyone else and say that CoM was very dark, especially when Riku Replica had his memories changed from Larxene (Can't remember if it were his memories) and when Riku Replica killed off Zexion.

Sora getting punched in KH2 Land of Dragons was very tragic as well.

EDIT: So Larxene didn't change his memories, but she did something to him.