Oh wait, so the current owner wrote that email?!
Yeh... there's a reason she's rich! Happy to exploit everyone she's ever met. Let me guess, she's about 30, her husband was about 80 and she basically shagged him to death for his bank account? Fucking grifter.
I've also done as a previous poster as refused to give donations to anything at all. Just tell people you haven't a pot to piss in, they can't really argue with it, you can't give what you haven't got. I can confirm I agree with that poster, it is most liberating. And don't ever "pay off that debt" or start showing up with visible signs of wealth, at least not at work. So far as they're concerned, you're on the verge of bankruptcy, always.
I'm guessing you want to keep your job. In that case I'd say nothing, don't buy gifts or donations, don't show up and tell them afterwards that you were unwell. Yep, every year, they can't prove anything. Having to go to such an event would be enough to make me feel sick anyway. I have enough of my colleagues at work, I sure as hell don't want to socialise with them outside of it.
If I was thinking of leaving the job, this would cement it for me and they'd get an email back saying that since you were informed at interview that O has more money than God and since you're upto your eyes in debt, you won't be participating in this scheme to voluntarily rob yourself blind. Then I'd email HR and resign before showing up to work for my last month and doing less than the bare minimum, because it'll annoy them so much when they realise they can't fire you and who wants to work for arseholes like that anyway? Not me. If you have some kind of skill there's always another job. I never had debt and saved from the start, so always had savings to fall back on though.