A woman who lit a cigarette as her car plunged into the sea also sent a final text to her partner telling him she loved him, an inquest has heard.
The woman's car came off the slipway near the chain ferry
Post-mortem tests revealed 30-year-old Helen Hogan died of hypothermia after her car went off the slipway at Poole, in Dorset, on 13 November 2005.
The mother-of-two, from Bournemouth, had argued with her boyfriend and was distraught and had been drinking.
Coroner Sheriff Payne recorded a suicide verdict on Wednesday.
Ms Hogan lit a cigarette and waited for up to five minutes while her car bobbed around in the sea, before it sank nose first.
She was found later that evening and taken to Poole Hospital but died in the early hours of the next day.
Several witnesses saw Ms Hogan drive into the sea, including Michael Warren who was fishing nearby.
He heard her black Rover estate screeching and revving and saw it go down the slipway at between 6mph and 10mph into the harbour water.
Mr Warren dialled 999 and told the inquest: "I was struck by the fact that she was just staring out of the front windscreen and doing nothing.
"I saw her lighter spark up a couple of times, she then lit a cigarette.
"As the car moved forward out of the harbour, towards the sea, I could see the woman still smoking her cigarette, still sitting perfectly still."
Ms Hogan's boyfriend, firefighter Mark Linzner, told the inquest they had argued on the day she died because she felt excluded from a family meal and felt like a "skivvy".
Pair of 'soulmates'
The twice married mother, whose children were nine and six when she died, previously suffered depression when an earlier boyfriend, Dean Story, was killed in a work accident, the inquest heard.
Her father, Neil McMullen, described Ms Hogan and Mr Story as "soulmates" and said only her children had kept her going at the time.
She later met and married Gareth Hogan but they separated when she met Mr Linzner in 2005 and the pair were said to be happy and planning to marry.
The final text she sent Mr Linzner referred to another former boyfriend and the father of her children, Russell White.
It said: "Russ will never forgive me. I hope you do. I love you."