A sub-postmaster whose life was ruined by the Post Office’s faulty accounting software has died without receiving his full compensation.

Jonathan Armstrong passed away in October from a heart attack at the age of 58.

His widow, Sarah, is now looking into claiming damages against the Post Office for his death, saying the “constant cycle of stress” after being wrongly accused of stealing due to the Horizon IT scandal took its toll on her husband’s health.

The Post Office said it was sincerely sorry to hear about Mr Armstrong’s death while the government said it was “striving to deliver justice as swiftly as possible”.

Warning – this story contains discussion of suicide and suicidal thoughts

Speaking about her family’s ordeal for the first time exclusively with the BBC, Sarah Armstrong said: “I truly believe that if we’d been paid out five years ago, he would still be here.”

The family also revealed that Jono, as he was known, had tried to take his own life.

It happened on the day auditors arrived to go through the accounts at his branch in Bexhill on Sea in East Sussex in 2014.

By then, the “losses” created by the faulty Horizon software had spiralled into tens of thousands of pounds and when Jono failed to come home Sarah feared the worst.

“We knew things were bad. We didn’t know where we were going wrong,” she said, adding that the situation felt so desperate, they’d spoken about potentially taking their own lives together.

“So when I realised he hadn’t come back, I thought that’s what he had done.”

Their daughter Becky drove to find Jono and by the time she arrived the emergency services had saved him.

Jono is one of 10 sub-postmasters known to have attempted suicide due to the scandal. The Post Office Inquiry also found that more than 13 may have killed themselves.

Jono was sectioned and spent nearly a month in hospital, followed by six weeks in a supervised residence.

The Armstrongs had moved to the UK from Zimbabwe in 2004, fleeing political unrest. A qualified accountant, Jono became a sub-postmaster two years later and Sarah ran the shop.

“It was a lovely little Post Office,” recalls Sarah. “We transformed it, quadrupling sales. It was very, very community based.”

They won numerous awards including Post Office Retailer in 2014.

But when Jono finally came home he found his contract had been terminated and the family faced a backlash from residents who believed he had been stealing.

He was “a broken man” suffering from anxiety, depression, high blood pressure and exacerbated diabetes, said Sarah.

She took on the role of sub-postmaster accepting the £43,000 of “losses”, to avoid Jono being prosecuted. But she had shortfalls, too.

Becky meanwhile had dropped out of university to run the shop and says she worried constantly about her dad.

“When someone has attempted suicide, you don’t know if they’re going to do it again… he was a shell of what he used to be. He’d just given up on life,” says Becky, now 33.

In 2015, they managed to sell the business and moved to Gloucestershire to be closer to Becky’s two other siblings.

Jono submitted his claim for compensation in 2000. An offer was made two years later, but it was just under a third of what he had claimed for – he rejected it.

It took him a further two years to resubmit his claim because of the time it took to gather new information, including medical reports.

But after waiting seven months, his case was transferred in April into a new appeals process, the HSSA, run by the Department for Business and Trade. Jono passed away before securing an outcome.

“He died without knowing, and that’s heartbreaking to us, because he deserved so much better,” says Becky.

Jono had only received an interim payment from the Post Office which he had used to buy a small caravan in a holiday park near Cirencester where Sarah still lives.

Sarah says Jono had been “obsessed’ about securing his full financial redress not just as vindication that he had done nothing wrong but to start a new life with his own permanent home and garden, “somewhere in the sunshine.”

“If he’d had that compensation, I think he would have been OK. We wouldn’t be worrying. He wanted to move away from England. He felt England hadn’t been kind to him.”

Becky managed to complete her degree and is now a sports coach. She’s also part of the Lost Chances, the group formed to campaign on behalf of the adult children of affected sub-postmasters.

She and her dad had chosen music for her wedding next year, including a “daddy dance” but she lost him just a few weeks later and now the planning has stopped.

“I’m heartbroken he’s not here to walk me down the aisle,” she says.

“He was kind, caring, funny, really into his music, always with the worst Dad jokes. But he was someone you could always turn to.”

Jono died just days before his 34th wedding anniversary at the end of October. Sarah blames the Post Office for everything that’s happened.

“Now we’ve got to fight for what he needed,” she says.

Four days after the BBC approached the DBT for comment, the Armstrongs received what their solicitor described as a significantly improved offer, which they are now considering.

A Post Office spokesperson said: “Postmasters and their families have suffered years of pain. It has taken them too long to clear their names and, in many cases, to receive redress. We are sincerely sorry to hear about Mr Armstrong’s death, and for his and his family’s experiences.”

A government spokesperson said: “We offer our sincere condolences to the family of Jonathan Armstrong. We are acutely aware how pressing the issue of compensation is for so many of the postmasters which is why we are striving to deliver justice as swiftly as possible.”

• If you, or someone you know, has been affected by mental health issues BBC Action Line has put together a list of organisations which can help.