Hideous morning - worst mom ever!

So today was the Book Fair at the kids school and the school had sent a note home saying that parents could come in with their kids from 8-9 before school for pastries and juice and shop at the Book Fair. I thought great! I won't have to feed them breakfast and they can get something from the Book Fair because it is Buy-One-Get-One Free. I don't know what I was thinking, why we would even go to look. Money is tight - it is always tight! My husband gets paid once a month and it is so hard to stretch the money after the 1st two weeks. Anyway my middle child is not a morning person and woke up on the wrong side of the bed because I had to yell at him to get him up. He was mad because he didn't even want to go to the Book Fair and was taking it out on me and his sisters. He was also complaining because today as a reward they are going to see the movie "Alvin and the Chipmunks" and he didn't want to participate. I signed the form that he was allowed to see the film but he was complaining about it. So we keep arguing back and forth about the movie and I'm saying that at least he doesn't have to do work and anyway people keep saying that the movie was good. So back to the Book Fair and it is complete mayhem! Too many people all at once. The mom in charge of the pastries is trying to set up the food so we go in to look around and what a gimmick! Getting one free just makes it more complicated. We were trying to find books and then you are forcing yourself to buy something so you can get one free. My 11 year old girl wants a journal type book that you answer questions and fill out stuff, but it is $15 so I tell her she can't get it. To make a long story short, we end up getting nothing and leave and by this time there are no pastries left to feed the kids. My oldest says she isn't hungry but my little one is and the boy he is just in a bad mood all around. We still have time before school, so I suggest running to McDonald's to get them something to eat. On the way out, my son sees someone in their pajamas and he feels like he is missing out for not wearing his pajamas for the movie and starts again about not participating. I offer to run him home to get his pajamas and he shuts down and is saying no, no, no! I'm getting so frustrated with him and under my breath I say to my oldest, "I'm about to punch him in the head, I swear". A pre-school teacher is walking by us and I'm mortified, because I think she heard! I never hit my kids or threaten them but now I feel like if she heard that I'm some kind of child abuser or hideous mom.