Diana is the kind of person who believes that '' either she's right or everyone else is wr...

Diana is the kind of person who believes that '' either she's right or everyone else is wrong '' if you agree with her, you're a righteous person but if you don't, then you're evil who deserves God's punishment.
Regarding her condemning Kael for the murder of that family that threatened her: if she truly believed that he was wrong, she wouldn't have taken advantage of the situation and marry Helios. She would have refused to become the CP a position that came from the murder of someone else. But no, she choose to overlook that, threw herself into a position bigger than what she could handle then when things didn't go her way she blamed everything on Hestia.
It's true what Helios said that Hestia doesn't really care about what's right or wrong but if you look at what she's accomplished, especially for the common people, you can't blame her. She's just outsmarted Diana and Helios and made her territory a better place in passing