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King, who won gold in the team pursuit at London 2012, suffered eight broken ribs and a collapsed lung while on a regular training route in south Wales.
The 24-year-old was in intensive care for two days and in hospital for 10.
"There were loads of things running through my mind, like I would never ride again," she told BBC Radio Solent.
"When I hit the floor I was fine. I thought I'd got off lightly. Then I felt excruciating pain as someone rode straight into my back and that's when all the damage was done.
"I could feel my ribs moving and was scared. I was in the road for an hour, it was raining. I lost feeling in my feet, which worried me. Three people had head injuries so I was last to be seen."
Cardiff-based King, originally from Hampshire, decided in October to switch from track to road cycling to ride full-time for team Wiggle Honda.
She was not named in the GB squad for 2014-15 funding year, and believes she has a better chance of getting into shape for the track in Rio by spending a season on the road.
King said the crash had not put her off road racing and is determined it will not disrupt her 2015 schedule, although she has not yet been back on a bike.
"In hospital I did three gym sessions - and that was with a chest drain in," said King. "A lot of people called me crazy, but that was just my way of dealing with it.
"I'm hoping to be on a static bike next week, but I won't be on the road for a few weeks - but I definitely will be back on a bike.
"I hope to resume full training at the start of the [new] year, so I'm still very determined."
King, who was runner-up to Laura Trott at the British Championships road race in June, added: "Initially I'm bound to be nervous, who wouldn't be? It doesn't change my focus to switch to the road.
"I've had bad crashes before and it hasn't stopped me. This is part of my job and was a freak injury. It was just bad luck."
Britain's Olympic track champion Dani King was "in so much pain, I couldn't breathe, couldn't cry," after a crash she feared would end her career.