@georgetakei Absolutely NTA. In fact, usually the sober one ends up driving or at least babysitting so their share is typically less, if anything at all. This person was being taken advantage of by people who saw her as a resource, not a person and certainly not a friend.
@georgetakei if someone wants to throw a group party, I'm in. But we're going to hash out the payment arrangements ahead of time. I don't drink out, and I am absolutely not on board with providing other people with booze anywhere except at my house or theirs. The thing is, you have to have that discussion up front. When the bill arrives it's a little late!