Whose Party Is This?

"Mom accidentally adds me into a group chat called "Happy Family". In the group chat, I saw Mom, Dad, and a stranger who's nicknamed "sweetheart".They are in the middle of organizing a birthday party for him. However, the thing is, tomorrow will be my birthday, which they have forgotten for the tenth time in a row.Mom says, "The venue must be dreamy. I want him to feel like an actual prince."Dad transfers a huge sum of money to "sweetheart". "Money is no problem! Just don't let Christopher find out about this. It'll screw things up for us!"I quietly take screenshots of everything, planning to find a chance to expose my parents' true colors and end everything with them once and for all.At that moment, my younger sister, who's always been great at her studies, sends me a screenshot via our private chat. It's a screenshot of the chat history between her and Mom."Mom, have you made preparations for Christopher's surprise party yet? You promised me that this is the last time you'd lie to him!""