At times, the solitude and separation from family and friends have plunged Jean Wyllys into despair. “I’ve been through moments of deep sadness, I’ve spent the whole night crying,” he said, speaking by phone from his new home in Berlin. “So I avoid thinking about it too much. I’ve kept very busy, I’ve written a lot.”

A writer and university professor, Wyllys won Brazil’s version of Big Brother before becoming one of the country’s best-known leftwing politicians, and the only openly gay lawmaker in congress.

But in January he resigned his seat and fled the country. “I left Brazil to stay alive,” said Wyllys.

The military dictatorship that ruled Brazil from 1964 to 1985 exiled leftist politicians, dissidents, artists and academics. Decades later, prominent Brazilian leftists and activists are again leaving the country, but this time they are fleeing death threats from rightwing extremists and supporters of President Jair Bolsonaro.

Other prominent exiles include the academic Marcia Tiburi, a former gubernatorial candidate for Rio de Janeiro state, the feminist campaigner Debora Diniz and writer and favela activist Anderson França.

“I didn’t want to come. It was an escape,” said França, who relocated to Portugal. “People like me are not safe in Brazil today.”

Anderson França: ‘People like me are not safe in Brazil today.’ Photograph: Theo Tajes

The four exiles all describe a cocktail of threats from paramilitary gangs, rightwing extremists and a nihilistic dark-web forum whose users spew hate for leftists, women and black people.

At times those threats coincided with abuse or defamatory lies shared online by high-profile followers of Brazil’s far-right president.

Diniz was put under police protection weeks before an unprecedented supreme court hearing last year to discuss decriminalising abortion.

Threats to kill her and massacre her students and colleagues at the University of Brasília arrived via WhatsApp and email. Diniz left Brazil after the hearing and is now working as a visiting researcher at Brown University in the United States; her husband is unemployed and she is far from her ageing parents.

“Leaving Brazil has a tremendous impact,” she said. “It is a horrible experience.”

The abuse and threats against Jean Wyllys began when he entered congress in 2011. Fake news stories claimed he had defended paedophilia; Bolsonaro – then a congressman – targeted Wyllys with homophobic insults and even told a television interviewer that Wyllys was “stimulating paedophilia”.

In 2017, Wyllys was given police protection inside congress. Last year it was extended to cover him outside congress and in Rio, and a bulletproof car was provided, but taken back before the election campaign. In November, the Inter-American Commission of Human Rights asked Brazil to protect him and his family.

“Even with a police escort, people threatened me openly,” he said. “They clearly said I would die when Bolsonaro became president.”

Marcia Tiburi, a prolific writer and university professor, was told last year by police contacts that paramilitary gangs were “watching her”.

These powerful mafia groups include serving and former police officers and have been linked to the Bolsonaro family. While he was a state legislator in Rio, the president’s son Flávio employed the wife and mother of one paramilitary leader who is now on the run. In 2018, two paramilitaries – both former police officers – were arrested for killing Marielle Franco, a 38-year-old Rio councillor known for defending the city’s black, LGBT and favela communities.

Marcia Tiburi: ‘There has been a witch-hunt in Brazil.’ Photograph: Courtesy Marcia Tiburi

Tiburi’s Rio apartment was broken into but nothing taken; rightwing activists began disrupting her book events; online threats said she would be shot during a book signing.

The Workers’ party provided security when she ran for governor of Rio – but it ended after she lost the election. She left Brazil and now lives between the United States and Europe. “There has been a witch-hunt in Brazil for a while,” she said. “I keep writing my books and doing my research.”

Anderson França, a writer and educator whose Facebook and Instagram posts denouncing racism, inequality and police violence are widely read in Brazil, has long received threats and racist abuse for his work.

After Franco’s murder and Bolsonaro’s election win, friends and colleagues told him it was no longer safe for him in Brazil. He moved to Portugal – and continues writing.

“We’re very worried about the people who stayed,” he said. “Is another activist going to die?”

França, Wyllys and Diniz all said they received death threats from users of an extreme racist and misogynist site that called itself “the biggest alt-right forum in Brazil”. (On federal police advice, the Guardian is not naming it nor its members.)

The site’s anonymous users discuss paedophilia, raping and killing women, “corrective rape” of lesbians, suicide tips and even plans to shoot up schools and universities to target Marxists and leftists. Over the years, the forum changed its name and moved to the dark web where it cannot be accessed using a normal browser; it recently suspended activities.

One of its early targets was Dolores Aronovich, a professor of English at the Federal University of Ceará in north-east Brazil. “They think the world’s true victim is the white, hetero male … that women control the world through the power of sex,” said Aronovich.

In 2011, some of its users expressed support for a gunman who killed 12 students – 10 of whom were girls – at his former Rio high school before shooting himself, said Flúvio Cardinelle, a federal police officer.

Cardinelle led a 2012 investigation that resulted in convictions for racism and sharing images of child abuse for two of the forum’s principal members, but they spent just a year in prison.

In December one of those men was handed a 41-year prison sentence for crimes including racism, inciting crimes, terrorism and sharing paedophile content. He has been filmed wearing a Bolsonaro T-shirt and giving neo-Nazi salutes. The second man remains abroad.

In March the Ponte human rights site reported that two former students who carried out a school massacre near São Paulo the previous month had sought advice from the forum’s users – some of whom later celebrated the slaughter.

Two officers from the cybercrime unit of Brazil’s federal police said they lacked resources to systematically fight virtual hate crime. There is a “general lack of efficiency in investigations because there is no dedicated structure”, said one. “The result affects us all.”

Leftists are not the only victims of such threats, they added. Congresswoman Carla Zambelli from Bolsonaro’s PSL party is one of several politicians under police protection after she and her family received threats from the same forum.

Zambelli said she believed the threats were motivated by misogyny rather than politics. “Our legislation over threats is very weak,” Zambelli said.

Jean Wyllys is rebuilding his life in Berlin, and hopes to study for a doctorate. He said he feels a responsibility to stay politically active.

“That’s what keeps me going, that’s what stops me falling into sadness,” he said. “It’s the chance to keep fighting.”