Hitomi? As in the one who crushed Sayaka's heart?
It was all a giant misunderstanding and it wasn't just because of that that Sayaka turned into a witch, everything piled on her at the worst possible time and Hitomi had no way of knowing that, nor did Kyousuke.
Kyosuke crushed Sayaka's heart because he was a dick in addition to Sayaka's difficulty to deal with what was happening to her. Hitomi had nothing to do with it.