If a real emperor did this he would risk civil war. If you kill your queen on trumped up charges it is one thing. If you kill her whole family which is most likely a aristocratic or wealthy family you will cause rebellion as none of the other aristocrats will allow it.
If you guys read the manga version she’s a totally pain in the ass. If I was in her shoes I would have beat the crap out of her I’m telling you. Sorry for swearing 🥺. I got mad 🥺.