You're just down, fed up and drained by the sounds of it. I'll make you laugh though.
I went to B&Q with a mate of mine in the summer for some bits for the garden. Me, my mate, her ds (autistic), my ds (ADHD and ASD) and my DD (NT). For the entire 20 minute drive there they were bickering constantly and winding eachother up. We parked up and turned around to face them all and read them the riot act due to their behaviour. They got out of the car nicely and waited at the path for us clearly wanting to get back in our good books.
(this isn't a stealth boast) I overheard another mother telling her kids off too, she then said "look at those kids over there, behaving nicely, they dont behave like a pack of animals in the car do they?"
At that moment I stopped and nearly bent over double laughing and had to explain that like her, we'd just read the riot act too.
My point is, all kids are annoying at times, especially your own and if anyone says otherwise they are lying. One day when you are out and about someone will be thinking the same about your kids as you are about other peoples "well behaved" kids at the moment.
Yeah they are draining, mentally, emotionally and physically. You constantly feel as though you are failing, stumbling along, wonder what the point is, can't deal with it any more etc etc etc etc..but you do because you have to and when you really think about it, you wouldn't want them any other way. I love my ds's SN, yes he's a major pain in the backside usually (like now, humming the starwars tune as loud as he can in my ear) but at 9, he's still a kid more than other kids at his age. They get to keep the magic of childhood for that little bit longer, it's priceless and worth every single moment of self doubt and wanting to just be on your own and/or run away from it all at times and just sleep.
Don't forget they are out of their usual routine this time of year so they are extra fraught and manic. They'll settle back to "normal" soon enough and you'll be longing for the holidays again.