Beatrice Huret faces possible jail time if convicted of helping Mokhtar -- whom she met while volunteering at the since-demolished "Jungle" migrant camp in Calais -- slip out of France under cover of night, on a rickety boat.
Arriving at the courthouse in the town of Boulogne-sur-Mer, near Calais, she said she hoped the trial would help others "understand what I did and why I did it" and said she took "full responsibility" for her actions.
"I am prepared to give up my life for him. The only thing that would bother me is that I would no longer be able to see Mokhtar if I'm in jail," Huret, who has a 19-year-old son, said.
Her lawyer said she would ask the court to dismiss the case, insisting her client acted for "humanitarian reasons."
She is being tried alongside three others accused of helping migrants make their way across the Channel -- two of them French and one Iranian.
The 45-year-old is one of several people around France who have been charged with illegally assisting migrants in recent months.
'Love at first sight'
Huret's journey from FN sympathiser to alleged people smuggler began on a cold day in February 2015 when she gave a lift to a young Sudanese migrant travelling to the squalid Jungle.
Before that, she had lived "a basic life" and voted FN like her husband, a border police officer who died of cancer in 2010.
Seeing the conditions in the Jungle gave her a new perspective on the plight of the thousands of migrants who flocked to Calais over the past decade in the hope of stowing away on a lorry bound for Britain.
"It was a shock to see all these people wading around in the mud," said Huret, a dark-haired woman with kohl-rimmed eyes, told AFP in an interview earlier this month.
She began volunteering at the camp soon afterwards and a year later met 37-year-old Mokhtar, who was among a group of Iranians who sewed their mouths shut in protest over the demolition of the southern half of the makeshift camp in March 2016.
When they first met, he spoke English but no French and her English was at best rudimentary. "It was just 'hello, thank you, goodbye', so I didn't speak to him immediately," she said.
"He got up to get me some tea. You got a sense of someone who was very gentle, very calm and then his look... it was love at first sight," said Huret.
With the help of Google Translate the pair struck up a relationship and after a few months he came to stay with her, her 76-year-old mother and 19-year-old son while continuing to seeking passage to Britain.
After a failed bid to stow away on a lorry crossing the sea, Mokhtar enlisted her help in another, desperate plan.
She agreed to buy a small boat for 1,000 euros and on June 11, 2016 towed it to a beach from which he and two friends took off across the treacherous Channel.
The boat sprung a leak en route but the trio arrived safely after being rescued by the British coastguard.
Huret, however, soon found herself in trouble. Two months after the crossing, she was arrested and charged with being part of a migrant smuggling network.
The couple have kept up their relationship over the past year, with Huret regularly crossing the Channel to visit Mokhtar in the northern English city of Sheffield where the former teacher has obtained a work permit.
She is one of several people to appear in court in recent months charged with illegally assisting migrants who have travelled up through Europe after crossing the Mediterranean in flimsy boats or stowing away in trucks travelling overland from Turkey.
Since demolishing the Jungle camp in October French authorities have taken a stern line on illegal migration, accusing activists who provide assistance to homeless foreigners of creating a "pull" effect.
In February, a 37-year-old olive farmer in southern France was put on trial for helping African migrants cross the border from Italy and giving them accommodation.
Cedric Herrou was let off with a suspended fine of 3,000 euros ($3,300) but was re-arrested last week for continuing to assist migrants seeking shelter.