As an artist and political activist, Ung Bun Heang was both an idealist and a passionate, unforgiving Cambodian nationalist.

Under the pen name “Sacrava”, he was relentless in firing off scurrilous cartoons attacking not only the prime minister and the Hun Sen regime, but equally the royalists, the late King Father Sihanouk, America, China and all of Cambodia’s neighbours, especially Thailand and Vietnam. No one was spared, not even the opposition when he felt they needed a poke with his pen.

But he paid the price. Heang knew he could never return to his beloved homeland from his adopted one, Australia. “I know exactly I am an ugly, black sheep in Cambodia,” he once said.

Above all, the artist longed for a new generation of Cambodians that would question, think critically and speak out with the sort of freedoms he had discovered abroad. After surviving the Pol Pot regime, Australia took him in as a refugee together with his wife Phiny and their baby daughter Kreusna.

“I love this country so dearly,” he never tired of declaring. He loved that Australian politicians could argue with such vehemence in parliament and yet meet afterwards as “mates” for a beer in the pub. That’s what he wanted for Cambodia rather than a politics of fear, revenge and bloodshed.

As the rebel son among five other children born to a wealthy Sino-Cambodian entrepreneur, Heang might have been expected to make a career in medicine or business. But his father accepted one black sheep artist in the family.

Heang first cut his teeth as a cartoonist working on Nokor Thom and other local papers in the war years that followed the overthrow of Prince Sihanouk in 1970. But that apprenticeship came to an end when Pol Pot’s silent guerrillas in black peasant garb marched into town as victors in April 1975. A new madness was unleashed in the revolution that followed.

During three and a half years of hell under the Khmer Rouge, the learning curve could not have been steeper for Heang and Phiny, both from privileged backgrounds. They were determined to knuckle down to work, endure and never give in to despair. For Phiny especially, the suffering was immense. Of her closest family, first her father was taken away, then one by one or in pairs, five of her siblings followed.

As the adage goes, what did not kill them made them stronger.

As an artist, Bun Heang’s most invaluable legacy is the series of 90 black pen drawings he created from his tortured memories of the everyday madness of what he, Phiny and their families endured in the name of Pol Pot’s insane revolution.

When this unique artistic record was passed over to the Australian National University in Canberra, Australia’s former foreign minister, Gareth Evans, observed how “the horror of that time is so brilliantly . . . graphically . . . movingly . . . even entertainingly captured by these magnificent drawings”.

A selection of the drawings was originally published in 1985 in The Murderous Revolution, the story of Heang and Phiny’s survival authored by Martin Stuart-Fox. Once settled in Australia, Heang worked as an animation artist for Walt Disney and other film studios.

When that work dried up after nearly all the animation studios moved offshore to Asia, Phiny and Heang opened a Cambodian restaurant in one of Sydney’s wealthiest suburbs. Despite queues of happy customers, hard work and long hours, both this and a subsequent restaurant did not pay off.

Determined to work harder than ever, Heang made a fateful decision to buy a small hardware business on the other side of Sydney. It proved to be a disaster and, when the bank foreclosed, the family lost their prized two-storey dream home. It was their pride and glory, the achievement of all they had worked for. Heang called the loss “our second holocaust”.

But he and the family took it on the chin. They stuck together, held their heads high and worked just as hard as ever. While Phiny continued her community liaison work with the New South Wales Police, Heang dedicated himself to a volunteer project. He created and painted a large Aussie-themed mural as an unpaid gift for a local public school.

That was by day. As “Sacrava”, he burned the midnight oil firing off his notorious salvos of politically explosive cartoons across the internet. Whether or not they opened minds and pricked consciences, they crystalised the unspoken fears and loathing of many Cambodians at home and abroad.

When his best friend and partner urged him to ease up, he replied: “Phiny, if I don’t draw I die!”

It says so much about Bun Heang that when he was stricken with terminal cancer, he laughed in defiance. “I take it as a compliment.”

And that he did. That was how he and Phiny had met every challenge and twist of fate since their marriage during the dark days of Pol Pot’s Khmer Rouge. Supported by a continuous vigil of family and friends, Heang fought to the end to make the most of his every last day on earth.

Ung Bun Heang, 60, died on Saturday, February 8. He is survived by wife Phiny, daughters Kreusna and Natalie Sita, sons Jesse and Justin, and three granddaughters. A first grandson is expected in June.