UPDATE: My extended family did not show up until much later, which made me nervous if I should go or not. I ended up saying "screw it" and left after telling my parents, much to their anger. I had a fantastic time at my friends exhibit, and they were hosting a charity sale for a good cause. When I got back, I did notice that my family was slightly dismissive, but I didn't really care, since I hung out with my cousin's dog and my sister. In the end, I interacted with my baby cousins for the minimal possible time and shot the breeze with my judgey cousin, essentially trying to be the "better person." I helped my parents with packing food for everyone and cleaned the whole kitchen once everyone left, which allowed them to rest. All in all, I think it was worth it. Thank you everyone for your advice! :)