I don't care about the bitch but Rosa did nothing wrong, this wasn't revnge for abandoning Jill and then Jill attacking MC after being alone, it would have happened anyway, this is because when they were in a party she liked Jill and lost it to Rosa and Nycto doesnt want to admit being a loser and invented a reason to punish Rosa.
Rosa left Jill after MC got kicked out for the problems caused because MC wasn't there to make them get pardoned + not upgrading the party gear and wasting money in heals, it was after Jill had gone loco and she couldn't close her eyes anymore.
I hope MC wil be able to heal her from the monstrous form, this author really hates any woman that even just vaguely slighted MC, again, Rosa didn't do anything negative to him.