Apprentice winner Stella English has told an employment tribunal that Lord Sugar "didn't give a s**t" about her job and told her he was just doing it for "the BBC and a bit of my own PR".
The mogul told English he had met his "obligations" to her when he broke the news that he would not be renewing her contract.
English who won Series 6 of the BBC1 show in 2010, is suing the millionaire business mogul, claiming constructive dismissal.
But Lord Sugar later described English as an "untrusting and suspicious person" who was full of "conspiracy theories".
During cross-examination at the East London Employment Tribunal Service, English said Lord Sugar told her during an unscheduled meeting on September 28 2011 that he would not be keeping her on.
English said: "He said to me 'Look, if you think Lord Sugar is shitting himself and that's why you're here, that's where you're mistaken - I don't give a shit.
"'I've met my obligations to you.
"'I did it for the BBC and the integrity of the show and a bit of my own PR and a bit of yours too.
"'But the fact is that I don't give a shit'."
Ms English said she could not believe Lord Sugar was not taking her life and future seriously.
"At this point I thought we were living in the real world, not in a game show," she said.
The tribunal previously heard that English worked for Lord Sugar's Viglen division for a four-month probationary period between September and December 2010 before being crowned the winner of the competition that month.
Chris Bates, the show's other semi-finalist, also carried out work for Lord Sugar in another of his companies during this period.
English carried on at Viglen after winning but, when she told Lord Sugar she wanted to leave in May 2011, she was offered another role at internet set-top box company YouView.
English told the tribunal she had felt pressurised by Lord Sugar to take the job.
She said he told him he needed a quick answer as the papers were going to print a story that she had quit the next day.
"I wasn't in a relaxed, comfortable position," she said.
"I would say that's a fairly pressurised situation.
"It was a completely new idea, something that I hadn't had any forewarning about. Therefore, it was something I needed to consider."
During the cross-examination, an email was read out that English sent to Lord Sugar on 24 December 2010., where she wrote: "I'm happy and people have been really kind to me."
English said: "Some people had been really kind to me. I don't dispute that.
"And some people hadn't been so kind to me. I'm not saying that every single person at Viglen was horrible.
"I'd just won The Apprentice. It was Christmas Eve."
On Tuesday, English told the Tribunal that when she looked through the company's accounts she realised that although it had a £60 million turnover, it only made an £800,000 a year profit.
She said that when she then emailed her boss, Bordan Tkachuk, to ask if she could discuss this with him - and that she had noticed that projects worth £1.4 million had not been invoiced - he sent her a scathing reply, copying in everyone else in the office.
English wept as she said he wrote to her: "I don't know what you're doing but this ain't how things work around here."
Reading out his own statement at the East London Employment Tribunal Service hearing today, Lord Sugar said he was surprised when she told him she was not enjoying the £100,000 role with him that she had won.
"I began to think that perhaps the reality of work rather than the glamour of showbusiness was beginning to bite with her," he said.
"Her time in the limelight was beginning to fade."