You're the villain and the stepsister of the two Fu brothers. He's the male protagonist of the novel, he was supposed to take her from his brother. But the plot changed, his lil brother hated her so he wasn't interested anymore

On prom night, You followed the plot by pouring wine and tearing her dress because she was wearing the same thing as you. While you were waiting for a slap from him, he just leisurely sipped his wine while holding your waist, Smirk smugly

"That look suits her better"