Mrs Williams, who described her husband as ‘jealous, controlling and possessive’ told the hearing: ‘I considered my marriage to be over and started divorce proceedings.
‘Then while on a night out I met a man, a solicitor, who had in the past acted for Darren on criminal matters. I was unfaithful to my marriage vows with this person.
‘One of Darren’s friends had learned about my brief affair and had threatened to tell Darren if I didn’t. I did not tell him but I believe someone must have done.’
Mrs Williams, 38, was at work in the Carol Ann’s hair salon in Newport, south Wales, when her husband burst in on August 19 2011. He opened fire shooting Rachel in the leg – and peppering the owner and customers with shot.
In a statement, Mrs Williams said: ‘Darren came with a black gym bag and pulled out a sawn-off shotgun.
‘I immediately thought he was going to kill me and shouted, “Dar, No!” He hit me across the head with the butt of the shotgun and I fell to the floor.
'I brought my leg up to protect me and he fired the first of two shots from point blank range. Then he discharged the second saying, “Rachel, I love you”.’
The inquest heard Mrs Williams wrestled the gun from her lorry driver husband before he ran from the salon.
The attack left her with serious injuries needing a ten-hour operation to save her left leg and extensive reconstructive surgery.
Days before the shooting, Mr Williams had been arrested following reports that he had threatened to kill the solicitor that his wife had slept with.
Mrs Williams told the inquest that her husband was a violent and jealous man.
She said: ‘As long as he got his own way he was okay, he was intimidating and knew that where I was concerned he could do what he liked. Darren was on steroids and anti-depressants which made him violent and unpredictable.’
Her husband was also on bail for domestic assault charges when he shot his wife.
He had appeared at Newport Crown Court on gun charges and engaged a local solicitor with whom his wife later allegedly started an affair.
His sister Rachael told the hearing: ‘Darren was told about the infidelity on his birthday, the 10th of August.
'I can only imagine his reaction – devastation. Before that he had blamed himself for the breakdown of the marriage.’
Detective Inspector Justin O’Keefe said: ‘Rachel had a liaison with a man who was known to Darren. This man had acted as his solicitor in the past.
‘On Wednesday August 11, we received reports he was on his way to kill that solicitor and he was arrested.’
The inquest heard if he had not killed himself, Williams would have been charged with attempting to murder his wife.
Williams’s other sister, Lisa Edwards said the day before the shooting he had told her: ‘I’m going to get Rachel back for what she did to me.
‘I’m going to get my revenge, I don’t want to kill her I want to shoot both of her legs. I’m going to go bang bang.’
Gwent Coroner David Bowen said Williams’ death was a result of his own action.
He said: ‘Whether it was due to the realisation of the enormity of what he had done, the irreparable breakdown of his marriage, his wife’s infidelity or his previous involvement with the police it is unnecessary for me to decide.’
He recorded a verdict that Mr Williams committed suicide while suffering an imbalance of the mind. After the hearing, Mr Williams’ mother, Barbara, said: ‘To sleep with his solicitor is unbelievable.
‘We are convinced that is what pushed Darren over the edge.’
The solicitor was not named in court, but Mr Williams’ family have named him as Gareth Driscoll of Driscoll and Young Solicitors in Newport.
Mr Driscoll, who lives in Cardiff, denies an affair with Mrs Williams.