Good on you, Maomao. Cruel nobles like Shenmei are so stupid. If you go around terrorizing and antagonizing everyone around you, you're only hurting yourself. No one will be truly loyal, making even more likely at some point, someone will be willing to make you pay and take you out. There may not be serious consequences if everyone supposed to protect you will just look the other way, glad to be rid of you.
Shenmei must think she's untouchable since she's the actual noble between her and her husband, even if he's the one with actual military power. But at some point, someone like her is hurting your standing more than it elevates it. Especially since they have a daughter in Lou Ran, so Shenmei is expendable.
Power is a spell so easily broken, so it's infuriating to watch this many people allow themselves to be miserable for this overgrown child.