On the evening of June 22, as Venezuela teetered on the brink of collapse, a small group of opposition activists met to discuss strategy in an upscale apartment in the leafy Altamira neighborhood of Caracas.

Among them was a bespectacled engineer named Roberto Picon Herrera, a well-known pro-democracy activist and nephew of iconic New York fashion designer Carolina Herrera.

As members of the opposition Mesa de la Unidad Democratica coalition began to plan their role in daily demonstrations to protest recent election fraud, spiraling crime rates and triple-digit inflation in a country where many were now scrounging for food, a group of 30 heavily armed military police in riot gear burst through the door.

Their main target was Picon, who was not a member of any political party but a civic-minded engineer working to devise systems that would ensure free and transparent voting in what many feared would be an upcoming sham election by an increasingly authoritarian regime.

Picon was hauled off by AK-47-wielding troops, their faces obscured by black balaclavas, to a notorious military jail in the center of Caracas where he was held in a communal bathroom cell for weeks.

Picon is the second member of the Herrera family victimized by the political and economic chaos that is sweeping Venezuela — a desperate situation that has mired the socialist country in daily violence and left many of its citizens to endure crushing poverty. Now, the normally discreet and reticent Herreras, bastions of New York society, are speaking up. And their outcry has coincided with a series of unprecedented measures directed at Venezuela from President Trump.

According to Venezuela’s authoritarian leaders, Picon, 56, is guilty of treason. Now the father of four is among nearly 500 political prisoners who’ve been rounded up by Venezuela’s unpopular socialist regime as it struggles to hold on to power.

In his regular weekly address to the nation, Venezuelan President Nicolas Maduro denounced Picon before the July vote for a Constituent Assembly and accused him of no less a crime than “the hacking and sabotage [of] the entire electoral system of Venezuela.”

But a month later, it was clear to the world that Maduro supporters had sabotaged the vote. In a widely ridiculed result, the Venezuelan government reported that more than 8 million voters had given them an overwhelming victory, even as independent election monitors put the total at just over 3 million who had gone to the polls.

At their home on the Upper East Side, the Herreras were outraged by the fraudulent vote that saw the ruling party take control of the Assembly, and by Picon’s arrest and continuing detention.

“He’s the Mahatma Gandhi of Venezuela,” Reinaldo Herrera, Picon’s uncle and Carolina’s 83-year-old husband, told The Post of their nephew. “He’s not political. He’s mobilized millions in peaceful demonstrations to defend the rights of the people. He’s been held incommunicado and slept on a bathroom floor, which he was also forced to clean.”

Herrera, who hails from a storied Venezuelan family whose ancestral home in Caracas dates to 1590, recently lost another nephew to the lawlessness that pervades the Venezuelan capital. In May, architect Reinaldo Herrera, 34, was shot dead along with Fabrizio Mendoza, a wealthy client, in a kidnapping gone wrong.

According to police, the nephew was simply in the wrong place at the wrong time. On the night of May 11, he met with Mendoza, a luxury car importer and currency trader, to go over plans for the renovation of his Caracas apartment. The kidnappers grabbed both men at a restaurant near the city center, and decided to kill Reinaldo Herrera so that he would not be a witness to the crime, according to Caracas police, who now have three of the six suspects in custody.

The vicious contract killing provoked an unusual public response from the normally discreet Herreras. Friends say they have been deeply concerned about Venezuela’s slide into authoritarian rule under its former dictator, Hugo Chavez, and now under his successor, Maduro. But in the past they have mostly suffered in silence, although their anguish has not been ignored by the powerful members of their inner circle, which includes their good friend Blaine Trump, President Trump’s former sister-in-law.

The Herreras have moved within the Trump sphere of influence for decades, since they all frequented Studio 54 in the 1980s. Carolina Herrera, 78, has dressed many of the Trump women for years. Ivana Trump wore her clothes and Herrera designed Marla Maples’s wedding dress in 1993. More recently, she made Ivanka Trump’s inaugural ball gown. And Herrera, who has dressed several first ladies, was one of a handful of designers to state publicly that she would happily dress Melania Trump after designers Tom Ford and Sophie Theallet refused to work with the Trumps earlier this year.

María Carolina Josefina Pacanins y Niño married Reinaldo Herrera Guevara, her second husband, in Venezuela in 1968.

Her first marriage to a Venezuelan landowner when she was 18 produced two daughters and ended in divorce. Reinaldo Herrera, an aristocrat, was the scion of a wealthy Venezuelan sugar cane plantation owner, art collector and philanthropist. His parents, Mimi and Reinaldo Herrera, spent part of every year in New York, where they had an apartment, and were fixtures in haute society circles in the 1950s and 1960s. Carolina and Reinaldo also moved between high society circles in New York and Caracas, where Carolina got her start in fashion working in public relations for Emilio Pucci’s Venezuelan boutique. The couple made a more permanent move to New York after Carolina established her eponymous fashion line in 1981, although they did not acquire American citizenship until just a few years ago. Carolina became a citizen in 2009, and Reinaldo followed suit a year later. The couple has two other daughters, 12 grandchildren and five great-grandchildren, Herrera told The Post. They also have a large family in Venezuela; the two nephews caught up in the country’s violence are related to Carolina by marriage.

But the Herreras have made no public statements on politics in their native country. Until now.

After their 34-year-old nephew was found dead in an SUV — shot in the head by the hitmen who police say earned $15,000 for the killing — the fashion designer, known for her flowing princess gowns and elegant suits for ladies who lunch, took to Instagram with a blistering message for Venezuela’s leaders:

“Our only hope is that the tragic assassination of our young nephew, Reinaldo and his colleague, Fabrizio will serve to mitigate the terrible carnage and murders that are committed against our youth in Venezuela,” wrote Carolina Herrera, whose father was an officer in the Venezuelan air force and once served as governor of Caracas. “The electoral results must be respected. The communist dictatorship must go.”

Months later, President Trump surprised everyone with some of the toughest measures of his presidency.

In August, Trump said he would not rule out a “military option” to stem the chaos that has overtaken the oil-rich rogue state. The statement shocked Venezuela’s ruling classes, with Maduro himself telephoning the White House shortly after Trump’s remarks. Trump refused to take the Venezuelan leader’s call.

“President Trump will gladly speak with the leader of Venezuela as soon as democracy is restored in that country,” the White House said, referring to a constitutional crisis which began in March when Maduro ordered Venezuela’s Supreme Court, which is stacked with his cronies, to take over the National Assembly, which was dominated by the president’s opponents.

Although the Supreme Court ruling was reversed three days after it was announced, it led to widespread demonstrations and violence, which reignited after the fraudulent election.

Trump was quick to reject the July 30 vote, and immediately slapped sanctions on the country. A day after the election — its aftermath left 10 people dead — the US Treasury Department’s Office of Foreign Assets Control froze all of Maduro’s assets in the US, and American companies were prohibited from doing business with him.

“Maduro is not just a bad leader. He is now a dictator,” White House national security adviser H.R. McMaster told reporters. “Recent actions culminating in yesterday’s seizure of absolute power through the sham election of the National Constituent Assembly represent a very serious blow to democracy in our hemisphere.”

Last month, at the United Nations General Assembly, Trump escalated his attacks on Venezuela. In his speech before world leaders, he spent the same amount of time talking about the Maduro dictatorship as he did on North Korea, Iran and Syria.

“The Venezuelan people are starving and their country is collapsing,” he said. “Their democratic institutions are being destroyed. This situation is completely unacceptable and we cannot stand by and watch. I ask every country represented here today to be prepared to do more to address this very real crisis.”

Last week, Trump added Venezuela to his controversial travel ban. Unlike the previous restrictions on countries, Trump’s ban on the South American country singles out government officials and their immediate families and does not apply to Venezuelans at large, although it also stipulates that visa holders “should be subject to appropriate additional measures to ensure traveler information remains current.” The White House contends that Venezuelan authorities do little to vet their own politically connected citizens. The vice president of the country has been accused of selling Venezuelan passports to members of the terrorist group Hezbollah and drug traffickers.

“Venezuela is a criminal regime that won’t respond to normal political pressures,” said Roger Noriega, a former assistant secretary of state under George W. Bush and a visiting fellow at the American Enterprise Institute in Washington. “It’s a dangerous threat right under our nose, and Trump is really determined to make an impact.”

No one was more surprised than the Herreras when the travel ban and the other tough measures were announced against Venezuela. As Reinaldo Herrera told The Post, “We had no idea something like this was coming, but we were thrilled when it arrived.”

Both Carolina and Reinaldo Herrera, who works as a contributing editor to Vanity Fair, welcomed Trump’s tough stand on leaders in their native country.

“I don’t think that President Trump is acting in an absurd fashion,” said Reinaldo Herrera. “Any opposition to the present president, anything that puts tremendous pressure on him [Maduro] and his government is positive.”

As for Picon, Herrera told The Post that he has been moved from prison to prison, and has spent weeks at the infamous El Helicoide, or The Helix. The modernist, spaceship-like structure was originally designed to be a drive-through shopping mall in the hills above Caracas. Today, it stands in the middle of a shantytown, and has been converted to a prison, where hundreds of torture crimes have been reported by human rights groups in the last three years.

After nearly three months in detention, Picon was finally allowed to see his family and hire a lawyer last month. And his cause is being taken up by opposition journalists who are getting the message out about what they say are trumped-up treason charges in social media posts and blogs.

“Roberto was not a politician and he never pretended to be one,” said columnist Leonardo Padron last week. “His mission was this: to perfect the civil machinery to allow citizens to express their political opinion in a civilized and democratic way.”

Reinaldo and Carolina Herrera say they are monitoring the situation daily and supporting their family in Venezuela.

“My nephew wanted to implement democracy in his country,” Reinaldo Herrera told The Post. “That’s all he ever wanted to do.”