CrayboffSheoThis may be late, but if you have the steam email verifications on trades, there's a slim chance you can get your stuff back? I'm not actually 100% sure, but the info in this thread, and the screenshots of the twitch chat is some pretty good evidence to show to valve.
Like I said I don't know if its a 100% solution, but its worth a shot I suppose.
No reason he should just play the victim and fuck over people who were doing something genuine.
No chance at all because it was you giving the items over. Valve expects you to do your own due diligence. If they can confirm your account was hacked, that's really the only time they'd give you back items.
You will not be required to confirm trades and will not receive email about trades. Steam Support will also not provide you with any assistance in recovering items that may be stolen from your account, for any reason.
That's the message in your [inventory] privacy settings, telling you the downsides to disabling email confirmations.
I don't think 'stolen items' only refers to items received from being hacked / actually going onto someone else's account. I would hope not, at least. Still, even if they don't do anything, it's still worth a shot - especially since there's more than 2 people involved, and the items were given with the intent to donate to a charity.