Katie Robertson was on her way to meet her fellow bridesmaids in Invercargill but she never made it.

Instead she was killed instantly in a head-on crash Old Coach Road, near Mataura in Southland, on February 15, 2019.

On Tuesday, Corrina Peterson was sentenced to 250 hours' community work, six months' conditional supervision with counselling, disqualified from driving for 18 months and ordered her to pay $18,000 emotional harm reparation for causing Robertson's death by carelessly using a motor vehicle while illegally overtaking.

A procession of Robertson's family read their victim impact statements before Judge Bernadette Farnan in the Invercargill District Court.

Robertson, originally from Invercargill, was travelling from her home in Dunedin to meet up with fellow bridesmaids before a wedding in Cromwell the next day.

Judge Farnan says Peterson drove about 1500km a week for her sales job and when she pulled out to overtake, was travelling at 109kmh and she was not crossing double yellow lines.

Peterson had about 340m of visibility when she pulled out, Judge Farnan says.

Judge Farnan says no decision today can take away the Robertson's pain.

Peterson had been willing to pay the reparations from her Kiwisaver account, Judge Farnan says.

Defence lawyer John Farrow says Peterson accepts full responsibility for her actions.

"She is at a loss as to how she did not see the deceased."

Peterson was not on her phone at the time.

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He says Peterson was not in a rush that day as she took an optional rest stop in Invercargill the night before.

In her victim impact statement, Robertson's mother Cathy says she does not believe Peterson shows any remorse.

"What you did has cost our family more than you could know, you have broken us," Cathy says.

Cathy has been diagnosed with post traumatic stress disorder since losing her daughter.

"I don't know if I can ever fully live again."

Robertson's partner Brodie, in his statement, says she was beaming that morning knowing she was travelling to Invercargill to see her family and to be a bridesmaid the next day.

"Katie made me the happiest man on earth. We made plans together to buy a house and travel overseas," Brodie says.

Her sister says "we have paid the price for your devastating decision."

Robertson's brother Daniel says "for a girl who's happy and bubbly, it's disgusting that this is how she has lost her life."

Outside of court, Cathy says she believes Peterson got off easy.

"As a family, we just felt there wasn't the remorse shown."

Peterson hung her head during most of the court proceedings.

"She didn't even look us in the eye," Cathy says.

"Katie was such an amazing young woman, we had messages from people she worked with in America.  She instantly made friends everywhere."