Hello Tessa, welcome to PC. I'm sure you'll find lots of support here. There is no point in forcing yourself to do something you don't feel like doing. If you don't want to go just stay home, relax. And don't feel guilty, everyone has ups and downs, we are all just humans. Call your friend and tell her/him that you're not feeling well, I'm sure she/he understands.
Take care, I hope to see you around here

sparkling