I would have to rewatch the cutscene with her but I understood it as her circumstances being pretty well known. I didn't think she was at a brothel either. I though she was sold off and married off to an abusive older man who was well known for his treatment over her. Her view is kind of twisted. Though the underlying drive is vengeance in a way, I think its also is a case of basically making others suffer her fate. In her view, the way the world is you are either the abuser or the abused. Right or wrong, justice and honor, all that stuff, is all just empty words.
Its twisted and crazy but she is a pretty broken person. Regardless of anything else, it was a system the Domans accepted that created her. That is why Hein says at the end that he will remember her words. He understands it was the Doman's own acceptance, for the sake of their own safety, of cruelty done to others that created her. To talk to her about doing the Justice and right and wrong after allowing her to suffer is hypocritical.
Again, that doesn't excuse what she has done but she does have some basis for her insane hatred. The fact she doesn't seem to hate the Garleans is also telling considering it was under Garlean rule her treatment happened. It makes me suspect she, and probably a lot raised under garlean rule, are taught not to question Garlemald. However there is a twisted logic to her viewpoint. Its kind of like a insanely, wrathful jealousy.
At least that is how I took it.