Bennett told Newshub that those physical attacks and death threats paled in comparison to the pain caused by "the lies" she faced in her time in Parliament.
"My welfare reforms are somewhat controversial, I'm a controversial character - I get that," she said.
"It was when they blatantly lied, and that then almost went viral and that hurt my family and that hurt me and I had zero defence."
Bennett was not pushed on what these "lies" were but railed against their ability to be shared widely.
"People can just tell absolute untruths about you and then it gets shared and shared and shared - and it almost becomes someone else's truth," she said.
Bennett's decision follows last month's leadership change in the National Party after Todd Muller and Nikki Kaye rolled Simon Bridges and Bennett. Bennett was also removed as the party's campaign chair and replaced by Gerry Brownlee.
She informed Muller of her decision at 9am yesterday, telling media he had thanked her for what she had done for the party and that she would be missed.
Bennett summed up her rise in politics, from "a 17-year-old solo mum who dropped out of school ended up being deputy prime minister of this country".
She said that making the call to quit was not "tough at all", and it was time to put herself first. Life was too short for regrets.
"I have had an incredible time in politics for the past 15 years and now I am looking forward to my next career."
She had been reflecting on what she wanted to do in the past weeks. She was "open to opportunities" in the business world and did not have anything specific lined up at this stage.
She will remain a National Party member.
She joked that she would like to stay married so she didn't plan to spend more time with her family, and she looked forward to more fishing.