Former MJM International employee Hugh McGinley has taken the East Kilbride-based company to a Glasgow industrial tribunal after claiming pressure and stress forced him to resign last year.
He said: "Staff who got on the wrong side of her had their lives made hell.
"In my six years there if staff had a dispute or got on the wrong side of Michelle their lives would be made hell.
"Several people were driven out the door."
Mr McGinley, 52, said he feared he was getting the same treatment days after the company was taken over by lingerie company MAS in February last year.
He said he worked weekends and at night to try to get accounts organised but he would be distracted by emails from Ms Mone.
One day, he said, he had to plough through emails from Ms Mone about her children's school fees.
He claimed Ms Mone told him in a meeting on February 18, 2013, also attended by then operations director Scott Kilday, she was worried about animosity between them.
He added: "I didn't believe there was any animosity. She asked if I had any issues with her. I said we had all this correspondence about school fees the other day and it was a total waste of my time. I'm working with figures that have to be accurate and checked.
"She more or less said that was her style and she would always demand information. I was either to like the way she required information or leave the company.
"Despite having the remarks made to me I still gave 100% for what I was doing for the company. It came across to me that Michelle didn't respect or understand the demands she was placing on me. She had no understanding of what I was doing for her. I felt I was left with no trust or confidence in Michelle Mone."
By November 2012, MJM was facing serious financial difficulties, the tribunal heard.
A buyer was sought and Ms Mone met the eventual buyers at a conference in Sri Lanka. The sale went through the following February.
Mr McGinley said he was "sickened" to learn a listening device had been found in Mr Kidlay's offices at MJM last year.
He added: "I was leaving to keep my integrity intact."
The hearing continues.