I'm in a small team, working closely together where some rely on others work to help meet deadlines. One of our coworkers in particular, is lazy which affects others work (they have to pick it up), constantly off, rude and in general annoying. For example- will argue about the smallest things, try get involved in others personal business and tries to claim work as her own (boss is aware of this).
We organised Christmas dinner/drinks Thursday night straight after work which she found out about after overhearing talk of it so is now coming. Now that others know she is going they want to cancel...then rebook somewhere else without her. In my opinion it's all a bit childish but I really don't want her to ruin my evening (30 hours a week is enough) so WWYD?