Talk to your co-workers about it. It's impossible for us to give you any good piece of advice. Your boss may be a prick. He may have been screamed at by someone higher or some client. And maybe he was just having a bad day...

All in all, it's not good for a boss to tell their employees that they're fucking up. unless he comes with a plan to fix it and it's actually better than what you guys were doing... So technically, he's the one who's messing up...