i can't stop comparing it to "jikogu shoujo".
first, the MC have happiness, not perfect but they can keep enduring harsh environment as long they have that happiness, and then the -soon gonna be- asshole victim took all their happiness, powerless to do anything they resort to Hell Girl.
as for this manga, add more assholes victims and remove the last sentence.
if you want satisfying revenge story like "dark massacre of hero" or "Redo of healer", never f***ing read this manga.