Frigide Barjot’s name literally translates as “Frigid Bonkers”.

But the French humourist is not laughing. She’s scared. “No,” she corrects herself. “I’m not scared. I’m very scared. Look at this…”

From somewhere in the indescribable chaos of her apartment in central Paris, Barjot, the unconventional leader of the French movement against gay marriage, produces an envelope. Inside, there is a paper handkerchief stained with what she believes is blood.

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“I’m being bombarded with threatening letters, email, telephone calls,” she says. “Before the law on homosexual marriage was passed, the threats came from the gay militants or the far left. Now they are coming from the homophobes of the far right…”

Since December, Barjot (her real name is Virginie Tellenne), a right-wing stage satirist turned political activist, has been the most visible face of protests against France’s gay marriage law. But now, extremists from the wild fringes of her own movement are threatening to attack her during a demonstration in Paris tomorrow.

She has asked for police protection, and is even seriously considering a boycott of her own demonstration. She may yet take part, but says she will walk away if threatened or insulted.

The threats against the 50-year-old Barjot are thought to come mostly from an ultra-right racist and homophobic group called Printemps Français (“French Spring”) which has gained prominence alongside the anti-gay marriage protests. The ultra-nationalist and xenophobic writer Dominique Venner, 78, who shot himself on the altar of Notre Dame Cathedral on Tuesday, was closely associated with Printemps Francais.

Barjot says she has become a hate figure for this disturbingly resurgent, violent ultra-right in France because she dismissed Venner’s action as “deranged” and “un-Catholic” and because she is “anti-gay marriage but not anti-gay”.

Yesterday, the French interior minister, Manuel Valls, said he was considering steps to ban Printemps Francais, which has also called this week for attacks on ministers, gay lobbyists and the media.

Is Barjot not simply reaping the whirlwind she has sown? Has she not, predictably, lost control of a movement that was never, at its core, as moderate, democratic or gay-friendly as she had insisted?

“No, these are people who want to divide France and to promote hatred,” she says. “They have a narrow conception of identity and aggressive beliefs which are not the same as our own values, which are based on the importance of the family and the needs of the child and common-sense.”

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“I entered this fight because I knew that, otherwise, the protests would be dominated by people like them: the far right and the Catholic extremists. I wanted to give a voice to the thousands of ordinary people, not all of them people of the right, who believe that gay marriage, in the way that it has been imposed in France, is an attack on the family and foundations on which our society is built.”

Barjot, once known for her raunchy, satirical stage act, now describes herself as “press officer to Jesus”. For this interview she was wearing jeans and a leather jacket and, beneath that, a pink sheepskin jacket emblazoned with the logo of her movement. For Barjot, this was remarkably conservative. Her usual style of dress is that of an ageing Barbie doll.

Her unconventional look, her previous career, and her past friendships with gay men and women, have long made Barjot a figure of suspicion on the far right. Paradoxically, her flaky, witty, cheerful presence also gave the movement a kind of respectability which has seen tens of thousands of ordinary, conservative, middle class people, young and old, to flock to the mass demonstrations against gay marriage since December.

Since the “marriage for all” law was approved by parliament last month, and signed by President François Hollande two weeks ago, the savage antagonisms within the movement have been laid bare. In their threatening messages, the extremists accuse Barjot of being a government “stooge” and a “fifth-columnist” for gays.

“This man who killed himself at Notre Dame, I had never heard of him,” Barjot said. “He obviously wanted to become a martyr, to inspire other people to do violent things. How can a man who claims to represent traditional values, and Christian values, commit suicide in a cathedral?

“I am worried about what may happen at the demonstration on Sunday… I want guarantees, for my own safety first of all. I entered this movement to rescue the family, not to lose my own skin and have my own family torn apart.”

Barjot is separated from her husband. They have two teenage children. Her apartment and campaign headquarters, not far from the Eiffel Tower, is a jumble of flags, leaflets, clothes, documents, newspaper cuttings, books, flowers, a crucifix.

Barjot has argued for five months that people can oppose gay marriage without being anti-gay. She argues that the newly enacted law should be amended by a future right-wing government to give gays an improved right to civil union, but not adoption rights. The radicals are opposed to any form of recognised same-sex partnership.

Despite Barjot’s self-proclaimed moderation, her own pronouncements often veer towards the Christian fundamentalist and anti-democratic. She says same-sex marriage is not just a change in the law but a “change in civilisation”.

By giving sanction to the “unnatural” notion of two parents of the same sex, she says the law will undermine the foundations of the family, but also society and “human civilisation itself”. Her movement’s logo shows a mother and a father holding hands with a boy and girl. The slogan is: “All born from a man and a woman”.

Does Barjot believe, as some of her co-leaders do, that there are laws superior to the laws passed by parliament?

“Yes, I do believe that. I believe there are fundamental beliefs, and even the common sense and conscience of ordinary people, which are superior to laws passed by politicians. That is why I believe that this battle is not over. Parliaments cannot go indefinitely against nature and common sense.”