Tired...so very tired

The manic pace of the passed few days has just hit. I'm tired. Okay, it's not like I've spent the last week mining for silver in Perth (I hope someone caught the Kill Bill reference), but I have been on the go like never before. And last night I kind of got chewed out by my boss for... well I'm not quite sure what! I have no fucking idea. I had to leave for 45 minutes to go to an orientation for my web course, and when I got back apparently the shit had hit the fan. Half of my staff was missing, and when they finally showed, my boss was with them and that's when he pulled me aside. I don't remember what exactly he said, but it was something along the lines of "When you tell me that you're going to be ready at a certain time, I expect you to be ready."
The plan was that everyone who was going to be working with me was going to get loaded up and taken over to our kitchen, where they would get everything together to start cooking at 8:15. Well, I had to take off for my orientation at 7:30, and when I left they were getting everything together. I figured that everything was fine.
Obviously, I was mistaken.
When I got to our kitchen, half of my staff was gone because they had to go back for a few supplies they'd forgotten. Well, the manager that was taking them to get the stuff also had to go let another group into their kitchen on the other side of campus. I guess this is where the crisis struck. There was some sort of problem getting into the building, and they didn't actually get in until 8:15 - the actual time that they were supposed to start cooking - and they still had to get the ovens warmed up, get their stations filled, etc. Well, needless to say, our boss was not happy about this delay, especially since we had 300+ pizzas to make. I guess he showed up and tore that manager a new one, in front of a bunch of the staff, and then came over to take the rest of his anger out on me.
I feel wrongly accused.
All I did was go to class!! I'm willing to admit that the timing was not the best, but there's nothing I could do about that. And is it my fault that the other two (count' em TWO) managers that were there couldn't handle things for the 45 minutes that I was gone?! Not to mention that the manager who now has a new orifice is the absolute least liked manager amongst the staff. It's quite unfortunate.
Oh, and to top it all off, we were short a delivery driver because the fourth manager - who managed to miss last night's wonderful events - mixed up the schedule.
Let's see if I make it through tonight without strangling someone.