Long post ahead but I totally hear you. I sympathize with you on having to spend the holidays with this toxic household and the resident demon spawn. I mean, oh my fucking god what an awful child. I dreaded spending a fortnight with my family because of my two-year-old twin brothers right from the start and - lo and behold - I'm now forbidden from interacting with the family, have been banished to my room because 'nobody likes me' and my mother speaks to me like I'm a piece of shit.
The reason? Because I confiscated a packet of baby wipes from one of my brothers, who is fond of pulling every available wipe out of the packet and playing about with them. It isn't just baby wipes either. He grabs and runs about with anything he can get his grubby hands on. These kids have zero boundaries and they think they can do whatever the fuck they want. They're also part of the worst kind of category when it comes to children: control freaks. Everything has to go their way, everything has to be about them and everybody else can go fuck themselves. And receive a good punch to the leg, whilst everybody laughs because they think it's 'cute'.
And because I'm the monster who dared to 'snatch' off him (because he'd totally give me the wipes if I asked for them. /end sarcasm), I'm basically told to live elsewhere if I can't get 'sort myself out'. Trust me, if I had the guts and the means to do so, I'd fucking hightail it out of here and never look back. Honestly, the only thing in the house that doesn't make me want to slam my head against a brick wall is the dog, funnily enough.
I've also had the whole 'you're making people feel uncomfortable because of your crazy behaviour towards the kids' lecture drawn out for me as well. Which I personally find rather funny. Christmas makes me depressed, the holidays in general make me feel depressed because I just feel suffocated by it all. So, yeah, forgive me if I have zero patience and time for a disobedient child. Ugh.