Similar thing happened to me on the old boat when the winch webbing broke right under the hook. Boat just disappeared out the rear view mirror. Webbing was less than 3 months old. Luckily we have an old mine conveyor belt made of reinforced rubber bolted to the top of the slip that runs out across the sand so no damage. Quickly tied the webbing directly to the boat and winched it back on.
Always keep a short rope attached to the winch post to act as a backup now. Does not get untied until the wheels are in the water.
Also the winch webbing now gets detensioned when towing or sitting idle to reduce the wear and instead I have a 5 tonne ratchet strap to take the load.