I had a similar situation on my road bike on a lane, bombing down hill.
Sacary ass sh*t to be honest, had visions of all those tour crashes where the hard braking is then followed by some wobbling and then a perfect somersault over the edge!
Brake. Pray. Find somewhere safe to land if needs be. Collect it and stop in time. Laugh like an idiot for 15 seconds while the adrenaline pumps. Get yourself together and realise how luck you are. Ride home more carefully.
Somerset, like 'Heartbeat' with newer cars!
Retro MTB: 1992 Cannondale M1000 Deore XT M730. 1992 Raleigh Dyna Tech Quantum Deore XT.
Retro Road: 1992 Eddy Merckx Corsa Extra Telekom Shimano 600 STI. 1993 Dyna Tech Ti Campagnolo Athena 8 Ergopower.
Modern: 2004 Wilier scandium Ultegra 6600. 2014 Wilier GTR Ultegra 6800.