How do i navigate the anxiety i have for a big family party this weekend?

1(21f) have a family party coming up on Saturday it is currently Thursday) and i cant stop freaking out about it.
Although im young ive been very successful economically/ career wise (thanks to our amazing jesus christ) ive always prioritized my school/social image. My family considers me the black sheep as this isnt very common amongst my generation in my family and ive always been vocal about defending myself whenever anyone wants to make me feel bad about it. I havent been around my extended family for a little over a year as there really hasnt been a need to. The last time i was around all of them i ended up having to defend myself against 4 grown me (my uncles and cousins) who would not stop openly shaming me for having a drink.
However this Saturday is my dear cousins party who also happens to be pregnant. I love her very much and know i cant/shouldnt miss out on this as she notified me 2 months prior (i work in medicine and she has always been so considerate of my crazy work life balance i love her sm.
However i can not shake off this feelings of almost nausea inducing anxiety and worry i get knowing that specific family members are going to be there. Its so bad to the point where yesterday i spent an insane amount of money on louboutin heels and couture dresses in order to make myself feel better. I know its stupid but sometimes shopping makes me feel better and i was just trying to cope (didnt help btw). I have never been open about any of this and it feels like im counting down the hours to the worst day of my life. Please i know its most likely because im young and havent had enough life experiences that i dont know how to emotionally regulate myself yet. I would appreciate it so much if i could know how some of you would handle/cope. Thank you sm.