@littlek,
Ack!!!!
I'd start with a good dummy spit here!!!
Oh...you already did....good.
I guess it depends what you want from your relationship with your sister in the future....and how damaging you think sucking it up vs having a go at her would be.
From the not involved Mt Olympus of holier than thou, I would suggest the debt might be punishment enough, without you needing to add more.
I understand how angry-making the years of splurge were, and it sounds as though the parsimony might be as excessive!
The stuffing sounds as though it was the coup de grace...but really, it was up to your parents to set a limit there.
I guess I'd suck it up, have dinner at home, and maybe have more of a splash-up with friends?
When you feel calmer, might be the time to have a word with your sister...or not.
I think sometimes people just are.