i don’t think i can go to my birthday party 😭

Hello, I’m using my girlfriends thingy so i can figure out what i should do. I work at a Mcdonald’s, and my 19th birthday is next week on saturday.. my family is throwing me a huge party that day, and i’m so excited. it’s just i talked to my manager and she said i’m not allowed to call off... i work from 8a-10p and I truly think i’m going to cry. i’m unsure what to do now. i let my family down.