Hi W, I appreciate your dilemma but I also have an appt. tonight that I really cannot miss that has been scheduled for some time now. Let me know what solution you come up with and I will do my best to help if I am able.
Did your W tell you should would be staying late at work tonight or did she just find out this morning? Funny how she griped at you for having to stay late and you told her ahead of time but she still wanting you to drop everything for her to be social. Now the shoe is on the other foot - she needs your assistance for HER JOB and she expects you to give it to her. Y'day when you needed her assistance for YOUR JOB she wasn't all that nice.
Don't take any action. Let her figure it out. Let her know you will be available to assist her AFTER your appt. That is what I would do.
