Sean Sullivan, 20, had only passed his test the day before the crash which killed Timothy Malone near Cefn Bryn Common, Gower, on 31 July 2016.
Swansea Crown Court heard Sullivan had ignored pleas from his passengers to slow down.
He pleaded guilty to one count of death by dangerous driving and one of causing serious injury by dangerous driving.
Sullivan also admitted two other charges of dangerous driving involving two other drivers.
Prosecuting, Ian Wright said airbag data from Sullivan's car showed four seconds before impact, it was travelling at 98mph and the throttle was at 100% at 5,000 revs.
"Essentially, his foot was touching the floorboard," he said.
The court heard Mr Malone, who was was staying in a nearby caravan with his wife, Yvonne Howard, was unable to take evasive action or avoid the head on collision on the country road.
Addressing Sullivan in court, Mrs Howard said: "I am haunted by the images of the terrible events of that night - the last time I saw him.
"I cannot heal my tattered heart and soul. I go to sleep in sadness and wake up to sadness. My face is wet with tears every day."
Judge Peter Heywood sentenced Sullivan to five years in a young offenders' institution. He will also be banned from driving for four years following his release.
Speaking after the case, Inspector Steve Davies of South Wales Police, said: "Our thoughts, as ever, are with the family and friends of Timothy Malone who lost his life in such devastating circumstances at Cefn Bryn in Gower, last summer.
"This tragic loss of the life has once again highlighted the consequences of a young and inexperienced driver, driving at excessive speed, which puts drivers, passengers and innocent road users at risk of serious injury or death."
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