OMG! I'm so sorry! I didn't realize I left you guys hangin' on why Hara killed Hitana! So here's a quick note on why!
The reason for that would be because Casella forced Hara to kill Hitana because if she didn't, Negima would be killed, Hara told Hitana and Hitana decided that she would take it, for Negima's sake. So it was all a misunderstanding between them. when Negima returned, remeber last chapter, they enetered the chunin exams and Hara told Negima the truth. after that Negima started t forgive Hara.
Again, SOOO SOORRY! I would continue, this but... I've kinda lost my inspiration! I'm terribly sorry!