I got that for being too bloodthirsty on my corruption playthrough.
She doesn't torture you in prison if you spare her. She shows you her tits and even tells you some info. The way I saw it, I beat her so she's mine. While that last bit is going to take a while, she's almost considering joining the Harem. Dani thought I was joking when I said I would seduce her and make her submit. Hell, she even laughed at my overwhelming power. I showed her.
Also, you already returned the favor when you brutally killed her lol. It legit don't get no worse than that. Well and she's living inside your head via memories. Even before that though, you fucked her up so bad when you fought her the first time. She's legit in a wheelchair. Hell, the 2nd time, she's in a fucking coma for months with her eyes fucked up and another hole in her.