Mistaken Identity: I'm Not A Mistress

My best friend and I go to a music festival together. There, my brother's girlfriend locks me in the toilet.

"Young women these days are so shameless—I can't believe you had the nerve to seduce my CEO boyfriend! I'm going to teach you a lesson today since your parents obviously didn't raise you right!"

She refuses to listen to my explanation. She pours dirty water all over me before slapping me in public and stripping me. Then, she brands me with an insult.

By the time my brother arrives, I'm tormented beyond recognition.