the story starts after being reborn but it doesn't explain why they all hate her, it could be because they feel guilty for loosing her also it just states that she was kidnapped but she is was happy with the grandma that raised her
Pampered by the Entire Family: Real Young Lady Went Mad After Reincarnating
I can just imagine how Tan Jing face was, I wonder if any of the students took a video and will upload it so that little brother can see her and finally get disillusioned and be amazed at his true sis