@lazerus56 Depends on what they did do or tried to do to her. Also, she's very into giving someone a taste of their own medicine and most of the targets are people whose murder would create a lot of fuss and investigation. However, by having Bu raped she gets punished and dishonored with only an investigation that ends quickly. If Bu died than her fiance the 4th prince would've taken it as an insult and push forth the investigation leaving no stone unturned. In LN, it describes the place she got tossed as a practically lawless area where a lot of foreign workers stay and are extremely pent up. There was an incident a while ago where a servant woman had made the mistake to cut through that area and had gotten gang banged as well. The foreigners were depicted as almost bestial, considering any woman who entered the area as up for grabs for sex, and not very familiar with the notion of getting a woman's permission or opinion before doing the deed.
Seems Chenyu is becoming more and more like her mother in letting her emotions run away with her and not thinking about what to say or do without considering the consequences first.
Reason she wasn't a virgin was because she and the 4th prince had been having premarital sex. To spice things up they'd been using the aphrodisiac which was why it was on her hand. Although now that she's been soiled publicly the 4th prince will break the engagement. After all, the marriage is just a means of convenience for him rather than him having strong feelings of love for her and he cares more about gaining enough favor to become emperor than her. So even though not her fault the culture will add insult to injury in considering her soiled goods and speak badly of anyone she marries so to avoid loss of reputation he'll break up.
All that is really fucked up... and it isn't even explained correctly. I will probably drop it sooner or later because it's becoming worst by the chapter imo.
Btw the way, thanks @Mathiason. Your comments are always helpful and needed to understand what the hell is happening.