Mark Jennens, 40, was accused of manslaughter when his mother died after a row at their West Midlands home over Christmas dinner in 2015.
The prosecution argued he threw her to the floor causing a fractured hip.
But after a jury cleared him, he said: "For the first time in 18 months I can look myself in the eye in the mirror."
Mr Jennens, of Brierley Hill, was the carer for his 78-year-old mother, who suffered from lung cancer. He admitted the pair had a difficult relationship.
"She was a Jekyll and Hyde. She could be lovely or she could be evil, you never quite knew what you were getting," he told the BBC.
Describing what happened on Christmas Eve, he said she fell after he picked her up by her arms in a "tragic accident" following their dispute.
"My mother has been a difficult character and I'd been her sole carer for 10 years," he said.
"She was being aggressive as per usual. Thousands of times she has been aggressive before.
"And this one time I wanted to cry to be quite honest. So I went to pick her up to put her outside the door for two minutes so I could sit there and have a sob.
"Well she went [fell] over and I phoned the police and ambulance."
His mother was taken to Russells Hall Hospital in Dudley, but later contracted pneumonia and died on 18 January 2016.
Mr Jennens said he was "absolutely gobsmacked" after he was arrested shortly after.
"Next thing you know I'm being done for manslaughter," he said.
During his trial at Wolverhampton Crown Court, it was reported the prosecution described what happened as "a cascade of events all led from a fractured hip which she suffered at her son's hands."
But Mr Jennens' defence barrister argued there had been a "break in the chain of causation" when Hazel was incorrectly administered Salbutamol in hospital two days before she died.
The jury cleared Mr Jennens in less than 90 minutes.
"It was never prison that bothered me," he said.
"No matter how difficult a relationship you've got with your mum you are always going to love them.
"My mum had terminal lung cancer," he said, adding the family didn't know that his mother had been told a year before she died she had six months to live.
He believes the case should never have been brought and that there were many gaps, including unanswered questions about her medical care.
"Now the jury has come back unanimously after an hour-and-a-half it confirms there was no case to answer," he said.
Mr Jennens said his family had "never doubted me for a second" and shared his relief.
"I'm more relieved for my sisters because in hindsight I think they have suffered more than me," he said.
He said he had been under enormous stress looking after his mother and has called for changes to aspects of social care.
His mother had refused help from social service which meant he was not able to get a "vital bit of respite if only for a few hours a week".
"People shouldn't be able to refuse care if there is a desperate need," he said.
A West Midlands Crown Prosecution Service spokesman said it had been decided there was sufficient evidence to prosecute Mr Jennens and it "was in the public interest to proceed with a prosecution".
He added: "Following a trial at Wolverhampton Crown Court, where prosecution and defence evidence was put to the jury, Mr Jennens was found not guilty to the charge put to him. We respect this decision."
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West Midlands Police said its investigation was "thorough".
"Our priority is and will always be to pursue the right and proper course of action in the interests of public safety and justice, especially when dealing with vulnerable members of society," added a spokeswoman.
Diane Wake, chief executive of the Dudley Group NHS Foundation Trust, said: "This is a very tragic case and our thoughts are with the family. We investigate every death in hospital and these form part of our mortality review process.
"No clinical issues were raised during our investigation and we would be happy to discuss any concerns the family have with them."
A son cleared of killing his mother has spoken of his relief, saying: "Who wants the stigma of being known as 'the bloke who kills their mum?'"