On the night of the Brazilian election, Bianca Gama cried as it became clear that the country’s next president would be Jair Bolsonaro, a far-right politician whose career has been marked by homophobia.

As the official result was announced, Gama’s girlfriend Priscilla Cicconi turned to her and said: “You were right. We should get married – before he takes office. Let’s do it.”

Gama and Cicconi were not the only ones to make such a decision: faced with a homophobic president-elect with close alliances to evangelical and Catholic churches, LGBT people in Brazil are rushing to claim hard-earned rights such as marriage equality and name and gender changes.

One notary association said that so far this year there had been a 25% increase in same-sex marriages in Brazil, and a 42% increase in São Paulo, the country’s largest city, compared with last year.

The rush to marry before Bolsonaro is sworn in on 1 January has become an act of resistance against the president-elect, who has described himself as a “proud homophobe”.

Bolsonaro’s vice-president, Hamilton Mourão, has said that while he believes marriage is only between a man and a woman, the incoming government does not intend to change the status of same-sex marriages.

Priscilla Cicconi and Bianca Gama decided to marry before Jair Bolsonaro takes office on 1 January. Photograph: Guardare Foto e Vídeo

Nonetheless, Maria Berenice Dias, the Brazilian Bar Association’s director of sexual diversity, has recommended that couples who want to formalize their union do so before the end of the year “as a precaution”.

On Sunday, after seven years together, Cicconi, 28, and Gama, 25, followed that advice.

At a no-frills community center near their home in São Paulo’s hardscrabble periphery, Cicconi (in khakis, suspenders and a bowtie) and Gama (in a sparkly white wedding dress), walked down the aisle surrounded by about 40 tearful friends and family members.

Among the guests applauding the couple were 17 strangers who volunteered to help arrange the wedding, organizing everything from a three-course lunch, to wedding photographs and live music afterwards.

The volunteers were part of an online movement to help hundreds of low-income, same-sex couples get married before the end of the year. “They are our angels,” said Cicconi.

Many couples are paying it forward and volunteering at other couple’s ceremonies: the wedding photographers, Fernanda Pinacio and Vanessa Cafasso, had also decided to get married before Bolsonaro’s inauguration, and offered their services to Cicconi and Gama for nothing.

“It’s such a hard moment for LGBT people in Brazil, but we’re supporting each other – and we will make it through,” Cafasso said.

The celebration dinner was prepared by chef Cris Mota, who volunteered after she and her partner got married in October. “It’s an incredible feeling to share a piece of our happiness in claiming our right to marry,” she said while preparing a pork ragu.

Volunteers are helping hundreds of low-income, same-sex couples get married before the end of the year. Photograph: Guardare Foto e Vídeo

Some couples and organizations are also planning collective weddings. One LGBT shelter in São Paulo has raised enough money to pay legal fees and throw a party for 100 same-sex couples later this month.

The same shelter has also raised funds to pay notary fees for 150 trans people who are rushing to legally change their names and gender before Bolsonaro takes office.

Pedro Pires, a transgender man, said he had put off changing his name because of the cost, but Bolsonaro’s election had given him a new sense of urgency. “These rights are fragile,” Pires said. “Once he takes office, we’re afraid we could lose them at any moment.”

Throughout his 30-year political career Bolsonaro has made no secret of his homophobia.

In a 2011 interview he said he would rather have a dead son than a gay son and in 2017 he was fined for “collective moral damages” over a TV interview in which he said he would never have a gay son because his kids “were well brought up”, and that he “didn’t promote bad habits”.

Days before the election, Bolsonaro signed a commitment with the Catholic church, which stated he would defend and promote “the true meaning of marriage, as the union between a man and a woman”.

An outright ban on same-sex marriage would be difficult to introduce, said Renan Quinalha, a law professor at the Federal University of São Paulo. Brazil’s supreme court unanimously ruled to recognize same-sex marriages in 2011, and any attempt to overturn that would be challenged by the Inter-American Court of Human Rights.

The wedding of Priscilla Cicconi and Bianca Gama. Photograph: Guardare Foto e Vídeo

Meanwhile, Bolsonaro and his allies would probably not have enough support in Congress to pass a law banning same-sex marriage, said Quinalha. “But it’s not written in stone,” he said.

Brazil’s world-renowned Aids program and anti-discrimination campaigns face a more immediate risk under a president who has vilified such efforts, said Quinalha.

In the past, Bolsonaro has said the state should concentrate on patients who fall victim to “unfortunate diseases – not deplorables who do drugs or get Aids from their promiscuity”.

Many gay people fear that Bolsonaro’s biggest immediate effect may be to empower homophobic rhetoric and street violence. The president-elect has promised to govern for all, but activists have already reported a frightening spike in reports of physical or verbal abuse on LGBT people.

“Many people were homophobic and kept it inside, but with Bolsonaro in the presidency, now they’re out and empowered,” said Cicconi.

Gama added: “He’s just one man, but he’s giving a lot of power to those who want to take rights away from us.”