I suppose I understand better. But at the same time, if the cruelty was impersonal and not exactly ever directed to this female assistant, her "revenge" still seems misdirected.

Unless there was some more personal misgiving done, or the model stands for something that is against the assistant's values, then the assistant is projecting her hate and using the model as a scapegoat. Add her envy and Nico's verbal abuse to the mix, and we have a ticking bomb.

The only thing that might have been the OP's fault is that she has been enabling Nico's behavior all these years.

Sorry, analyzing the nature of human cruelty is an interest of mine.

The story is intriguingly tragic to say the least.