Babysitter frustrations!!!

Does anyone ever get frustrated with their babysitter? I had a "situation" with my babysitter today, that somehow turned around being my fault and her getting angry with me.
She was suppose to watch my girls tonight so we could go to my husbands Christmas party. She was suppose to be at our house at 5:30, but, called at 2:30 to "ask" if she could come early, so she could leave early because she was so overwhelmed & stressed with school (college). She has put me in these situations before, taking advantage of my good nature because she knows that I will say "No, don't worry about it. Don't come", which is exactly what I did. Of course I was kicking myself for not sticking up for myself, as I never do, so I called her back to tell her my frustrations and how disappointed I was at the situation. Somehow, she turned this around and made me look like a witch because she was doing me a favor by coming early and other "Moms" would have told her that she had to come and couldn't leave early. It really upset me that she tried to turn this around and make me feel bad. In my opinion she should have to deal with the consequence's of her actions and face the music. In this case, it was me getting upset and telling her that I was upset.
I'm really angry and very upset with this situations. She has been our sitter for 3 years and my girls love her. I feel she is going thru life changes right now and acting out in different ways. I think she has taken on too much and the pressure is getting to her. I feel bad, reason being I told her not to sit. I felt I was helping her, however, I also felt I needed to let her know I was disappointed and felt she put in a loosing situation. No matter what I did or said, I was the bad guy. If I would have told her to come, I would have worried about the girls all night seeing as how she was so "stressed". I wouldn't have enjoyed myself at all. I should have just went and taught her a lesson on commitment and "growing up". However, I don't feel that is my place. I am an adult and do care about her and worry about her. I guess I would rather have her angry with me, than put added pressure on her by watching the kids.
AHHHHHHHHHHHHHHHHHHHH!!!!!!!
Anyone else face issue with babysitter related or not related?