I'm M in an R-rated Ruined World

"You should have expected this from the moment you abandoned me for my brother." When I came to my senses, I had possessed the body of a character in a dark, mature-rated story. "From the moment you threw me away." He was the former fiancé who had been miserably discarded by the original owner of this body. And now, it seemed to be the very moment he was starting his rebellion. "I've been waiting for this day." He killed my brother, who was once my fiancé. He killed my father. He even killed my mother, who had opposed me. "Beg for your life." And ascended the throne. "Can't do it? You laughed when I begged like a dog." The blade pressed against my neck stung as it tore my skin. ...