Emile Cilliers appeared to have it all. He was a successful soldier, an excellent athlete, good company and seemed a decent family man.

His Facebook page, which he continued to update while on trial, shows him in his military finery, taking part in army expeditions and international competitions and enjoying time with children or relatives.

But as Winchester crown court has heard, there was a much darker side to him than the images would suggest.

Cilliers mentally bullied his wife, Victoria, cheated on her with at least two women and contacted sex workers. His love of the high life – trips abroad, smart cars, big nights out, fine clothes – left him debt-ridden.

When he saw the chance of a new life with another woman, plus the opportunity to clear his debts by pocketing £120,000 in life insurance, he took it and tried to murder his wife.

His first attempt was relatively prosaic. He tampered with the gas supply at the home they shared in Amesbury, Wiltshire, hoping to cause an explosion while he was out at work.

When that failed, he opted for the extraordinary: he sabotaged his wife’s parachute, which resulted in her falling 4,000ft (1,200m), surviving only because of her slight frame and a landing in a soft ploughed field.

Prosecutors and detectives were shocked at how calm Cilliers remained even after he came under investigation. They saw him as a cruel, cunning chancer and a pathological liar.

Ian Harris, of the Crown Prosecution Service’s Wessex complex casework unit, told the Guardian: “Anyone hearing this case cannot fail to be struck by the callousness, the deliberation that went into the two attempts to murder someone he had said a few years before he would love and protect. It was a shocking betrayal.

“It’s quite clear that Emile Cilliers was trying to engineer a situation where he could kill his wife, run off with his lover and collect the money from an insurance policy and have a lot of sympathy because his wife had apparently died in a dreadful accident.”

Harris paid tribute to Victoria Cilliers, who has two children with Emile. “She thought she was going on a routine parachute jump. To her horror, her main parachute and her reserve failed her. She miraculously survived. When she came round she found that all her worst fears about her husband were confirmed and police had begun an investigation into whether her husband had tried to kill her. It’s been an extraordinarily difficult situation for her.”

South-African-born Cilliers arrived in the UK in 2000, by which time he had two children. He worked on farms and in pubs in the UK before meeting his first wife, Carly. They married and had two children.

One day he popped his head around the door of an army recruitment centre. “There and then I decided that was what I wanted to do,” he said in court. Cilliers dreamed of joining the SAS but instead completed a physical instructor’s training course, joined the Royal Army Physical Training Corps and rose to the rank of sergeant.

In January 2009 he suffered a serious knee injury while skiing with the army, and at that time he said he realised his marriage was in trouble. Cilliers and Carly separated and Victoria, an army physiotherapist, helped his rehabilitation. They began dating in March 2010. Both enjoyed sport. He was a rock climber and rower as well as a skier. She was a fine parachutist with 2,600 jumps under her belt and an instructor.

They married in South Africa in 2011, and Cilliers earned money to save for the wedding by packing parachutes. It was those packing skills that later meant he knew how to sabotage his wife’s parachute.

The marriage did not thrive for long. Victoria Cilliers was expecting their second child when her husband met Stefanie Goller via the dating app Tinder while skiing with the army in Austria in November 2014. Cilliers lied to Goller that his marriage was over and the child his wife was expecting was not his.

Cilliers was also continuing to see Carly and contacting sex workers. He arranged to meet one woman and film them having sex. He insisted this did not actually happen but explained in court he was a “very sexually active person”.

Victoria Cilliers suspected he was not being faithful. In police interviews and in the witness box at Winchester crown court she described how their relationship was under pressure.

“He was constantly on his phone, it was ridiculous,” she said. “I wasn’t allowed anywhere near it.” He would stay out late or away and she found condoms in the house and car.

She was frightened. “I was scared, panicky, everything seemed to be going massively pear-shaped and I didn’t really understand why, I didn’t understand what I had done wrong. I felt like I was living on a timebomb, not knowing if at any point he might turn around and say ‘I’m off’.”

She tried to keep the relationship alive, messaging him: “I love you so very very much and our life together and our plans for the future you are and always will be the love of my life.”

On 30 March 2015 Cilliers made his first attempt to kill his wife by tampering with a gas pipe. It failed and she texted him: “Are you trying to kill me?”

Cilliers brushed the idea off and asked his wife if she fancied making a parachute jump the following weekend to cheer her up. She told him she would love to. At exactly the same time he was texting Goller: “Have I told you lately that I am massively in love with the most amazing woman in the world? I want my life with you to start now.”

Though she had been parachuting since she was 16 and has described the rush as being like a drug, her fragile mental state meant Victoria Cilliers was not looking forward to her jump at the Army Parachute Association at Netheravon in Wiltshire on 5 April.

“I did not talk to anyone, I was quite tired and emotional by that point. I just put my goggles and my helmet on and put my head down,” she said. “I remember the pilot giving me a smile as I went out. Usually that’s the part that I love, the cold rush, the smell. And it just did not hit me.”

She tried to open the main parachute but it was full of twists. She cut it away and attempted to deploy the reserve. It did not work. One witness said the reserve canopy looked like a bag of washing while another said Victoria Cilliers was being thrown around like a rag doll.

“I could not figure how to slow it down,” she said. “It was just getting faster and faster and faster. The speed was unreal. The last thing I remember is trying to get some kind of control, then everything went black.”

Nobody watching thought she had a chance but she survived and was airlifted to hospital with fractures to her pelvis, several vertebrae and ribs.

When she woke up her husband was at her side.

Cilliers exchanged hundreds of messages with Goller while sitting next to his injured wife in hospital. One said: “I can’t imagine anything like that happening to you, all I can think about is you.”

Following a major operation, Victoria Cilliers told her husband she loved him. “He didn’t reply, which is harsh in that situation, really fucking harsh,” she said. She remained in hospital until 22 April. “I came home and just cried,” she said. “We just sat in silence that night, I couldn’t stop crying.”

By then a police investigation had been launched. At first detectives did not know if they were dealing with an accident or crime. But experts who looked at the parachute were shocked at how tangled the lines of the main were and could not understand why two of four slinks – kit that keeps the harness attached to the parachute canopy – were missing.

A US company has built and sold more than 40,000 reserve parachute canopies with slinks fitted and there have been no known issues of them failing anywhere in the world.

The British Parachute Association held a board of inquiry and concluded that between 2005 and 2014 about 2,300,000 sport parachute descents were made in the UK – and there had never been an instance of both the main and reserve failing.

Detectives probed Cilliers’ life and found out about his affairs and his debts. He was arrested on 28 April.

They established that the parachute Victoria Cilliers used had been hired out the day before she jumped. Her husband had taken it into a toilet at Netheravon and must have sabotaged it there before storing it in a locker overnight. At the family home in Amesbury they found flecks of blood next to the gas pipe that had been tampered with and he was charged with two counts of attempted murder.

In court, however, Victoria Cilliers was not always helpful to the prosecution. She said she had exaggerated some of her testimony to police to paint her husband in the worst light because she was so upset at his infidelities. It was not clear whether she believed the case against him.

Clearly there are no winners. Cilliers’ six children and the women he deceived his wife with are all victims.

Asked how she felt, Victoria Cilliers said: “Empty, alone, angry that all the time over the years I’ve had my little suspicions and niggles, and he has made me feel really bad and blamed my past insecurities.

“My intuition was right, that makes me angry and upset. What I thought was a reasonable relationship and family, he’s just torn apart.”