Michael Smith overtook in a dangerous manner before ploughing into a car coming from the opposite direction.
He had also been using his mobile phone shortly before the crash, on the A472 between Pontypool and Usk.
Cardiff Crown Court heard that the 43-year-old would have needed at least 176 metres of open road to perform the manoeuvre safely, but there was less than 63 metres.
It could not be proved that he was using the phone when he collided with the other car.
But when Smith was arrested he admitted making illegal calls and texts from his hand-held mobile during the drive in October 2005.
Smith, of Brynheulog, Griffithstown, Pontypool, suffered minor injuries.
He was found guilty of causing the death of 53-year-old David Brown by dangerous driving.
Martin Kelly, prosecuting, told the court: ‘Smith was using his mobile phone on his journey that morning. He sent the long text message barely two minutes before the tragic fatal crash.
‘His stepdaughter replied to the message at the very moment the fatal collision took place.’
Kelly said Smith tried to overtake in an ‘incredibly dangerous manoeuvre’ when he crashed his 4x4 into the oncoming driver.
Susan Ferrier, defending Smith, asked for the lowest possible sentence.
She said his wife was expecting their second child in April and that he was already father to a toddler and stepfather to the daughter of his previous partner who had died ‘in tragic circumstances’ just days before the crash.
She said he was genuinely remorseful for causing Mr Brown's death, but understood there was little he could do to ease their pain.
But Judge Philip Richards told Smith: ‘It is inevitable that a custodial sentence has to be passed.
‘The carnage on our roads is such that until it is appreciated that driving of this sort will result in prison sentences it is very unlikely that the carnage will be reduced.
‘I have great sympathy for your family, but it's not as great as the sympathy I have for the family of the deceased. Whatever I do today will not mean that the burden on your family will be greater than the burden on them. Their burden is permanent, it is one of loss and it is immense.’
He told Smith his driving fell far below the standard expected of a careful and competent driver.
‘It was in my judgment a very bad piece of driving demonstrating a gross error of judgment and it has had the result of killing a wholly innocent member of the public, who was doing nothing else but driving safely on his own side of the road.
‘You also chose to use a mobile phone to conduct text and telephone messages whilst the vehicle was in motion at a fast speed which is an incredibly bad piece of driving itself.’
He said that while he accepted Smith was a man of good character, he had to take into account that he had previously been disqualified from driving for speeding. Smith was also disqualified from driving for four years.