After I picked myself and the bike up, the ride leader apologized. He admitted that he had been overzealous with his braking and hadn’t considered the consequences, which brings up a few more good takeaways from this situation. If you’ve got riders behind you, signal what you’re going to do with a hand gesture, a warning flash of the brake lights, or, if you’ve got headsets, give them a verbal warning. If it’s too late, then just pass by and go back. There’s less shame in missing a turn than ending up in a heap on the side of the road.