After Being Secretly Replaced by My Mother for 18 Years, I Chose to Save Myself

I am my mother's only daughter, but she only likes my cousin who was born half an hour later than me. She would praise my cousin who scored 80 points on the exam for being excellent, but she would beat me up because she thought I was competitive when I scored 100 points. She gave tens of millions of jewelry to her cousin as a birthday gift, but all I got was a humiliating scolding that didn't deserve a birthday. Until I accidentally learned that she secretly replaced my cousin eighteen years ago. I finally felt relieved that she was not my mother. I found my aunt and happily told her the truth. Aunt Shen Congmei just looked at me jokingly and said mockingly, "Don't you know? I exchanged you back eighteen years ago."