A little self loathing never hurt anyone

I kind of hate myself right now. It'll pass. It usually does, but this time is more intense. I lost it yesterday. It could have been worse, much worse, but I still feel like total shit. I'm not sure how to make it better, or if I can.
I had a craptastic afternoon yesterday. After teaching my classes, I had to attend a 2 hour meeting in which I (along with my fellow teachers) was told that I am not good enough. Not only am I not good enough, but that, unbeknownst to me, I am a racist and that by simply showing up to work, I violate the civil rights of every student I come into contact with who is not white. My skin tone is apparently more indicative of my personality, biases, assumptions, values and beliefs than are my practices and the opinion my students hold of me. What. The. Fuck. Ever.
So I leave the meeting, glad to be done, missing my boys and excited to go pick them up and head home for some quality mom time. Yeah. Not so much. I get there and the babysitter looks like she's had her ass kicked three ways from Sunday. I guess all four boys tag teamed her. Vic cried and had a melt down every time something he didn't like happened, refused to take a nap and screamed at the top of his lungs when she put him down for one. Naps are not optional at this point. Os wasn't feeling well because he got his first round of vaccinations on Tuesday. Diarrhea, crankiness, lots of the crying for no reason. The other two boys she watches are still in boot camp-still learning the ropes of the place so they act up all the time because they don't know any better yet. So fun!
I walk in and Vic immediately starts acting up-ignoring me, ignoring the babysitter, pushing his little friend, just being an ass. So I tell him to knock it off and get ready to go. He needs his shoes, back pack, yada, yada. He walks off. I tell him we're leaving and he starts screaming at the top of his lungs, seriously, like he's being beaten. He doesn't want to leave. He doesn't want to pick up the toys he threw all over. Whatever. He goes into total meltdown mode. Time out doesn't help. He just screams louder. Swat on the pants doesn't help. He just gets pissed and gets louder. So I drag his ass out to the car and tell him he can't get in until he's quiet because I can't drive with him screaming like that. Takes a few, but he finally calms down. I get Os into the car, load Vic, get in myself and head down the road. Vic starts screaming again. He wants his music. No. Ya don't get to dictate what we do or what we listen to in the car if you get in trouble at the babysitters. All privileges go away. He knows this. Meltdown x10. I have never heard my child scream like he did yesterday afternoon. Never. He was out of his ever loving mind. So I pull the car over on the side of the road, screeching tires in the dirt and asphalt and everything. I get out, march over to his side of the car, open the door and lean in to talk to him. He screams louder into my face and won't stop. He just won't stop. I'm yelling and I can't hear myself over his screams. He was that far out of control.
I slapped him.
I didn't hit him hard, just enough to get his attention and get him to stop screaming long enough to breathe.
But I slapped him.
I slapped my baby in the face.
I didn't know what else to do, but I instantly regretted it. I pulled him out of the car and told him to take a few deep breaths to calm down. He just kept wailing. So I pulled him into me for a hug and told him I loved him, that I was sorry I slapped him and that I never wanted to do it again. But I also told him that his behavior was out of control. There was no reason for it. He wasn't hurt, in danger, or sick. There was no reason for it.
He just melted into my shoulder and told me how sorry he was and that he 'wubbed' me too. Then he asked if he could get back in the car because the traffic was scary. So I loaded him back into the car, got in myself and then drove home.
He was the perfect kid for the rest of the night.
As soon as he was in bed, I cried. I cried for a good hour. I feel like the worst mother ever. I know that it probably isn't a big deal. He'll forget it ever happened soon enough.
But I won't. I lost control. I would not tolerate anyone else doing what I did to my son. I can't excuse it in myself either.