An aspiring teenage theatre star developed an eating disorder after the "petrified" 15-year-old was groped by entertainer Rolf Harris, a jury has heard.
Tonya Lee, now 43, who has waived the usual right to anonymity given to alleged sex offence victims, claims that Harris touched her when she travelled to Britain from Australia for the tour in 1986.
She said she lost 9lb-13lb (4kg-6kg) after she "stopped eating" and would "throw up" during the six-week trip. After she returned home, she abandoned her dream of becoming a stage star.
Ms Lee said: " I just wasn't there any more, I lost that passion."
Southwark Crown Court heard that Harris met the performers from the Shopfront Theatre Youth Group when they arrived at London's Heathrow Airport in May that year, and later went for dinner at a pub with them.
Ms Lee had been singing, and said the veteran performer told her she had "a lovely voice" and invited her to sit on his lap.
She said: "I could feel that there was some movement happening beneath me. He was moving back and forth rubbing against me.
"It was very subtle, it wasn't big movements. Everything just seemed to be going on as normal."
The jury of six men and six women was told that Harris started to pat her on the thigh, and then: "He began to move his hand up my inner thigh."
She said she felt "very uncomfortable" as Harris touched her genitals over her clothing, and she "started to panic" before rushing off to the toilet.
"I was wondering what to do, 'How can I get out of this?', and also I was confused. The whole time this was happening just normal interaction was going on," she told the court.
Ms Lee decided not to tell anyone because the group's artistic director, Kathy Henkel, was friends with Harris, and she felt confused.
When she came out of the toilet, Harris was waiting outside, the jury heard.
The alleged victim said: "He came up and I don't know the exact words but it was something like 'I just want to chat to you some more'.
"I was intimidated because I felt quite claustrophobic."
Harris got her in "a big bear hug", and put his hand down her top and fondled her breast, it is claimed.
Ms Lee said: "I was petrified... I was in shock."
She added: "I felt stuck. I felt like I couldn't move. I was petrified, I froze."
Harris then touched her intimately, it is claimed.
Ms Lee said: "I just wanted to burst into tears at that stage, and I just wanted to run."
She added: "I was gobsmacked, I was shocked. Completely in disbelief."
Harris is accused of 12 counts of indecent assault between 1968 and 1986, all of which he denies. Three of the charges relate to Ms Lee's claims.
She said after the alleged assault she rushed back into the toilet.
"I was quite emotional, so many thoughts were running through my head. I couldn't believe what had happened. I felt disgusting. I did not know who to talk to."
Ms Lee said she thought no-one would believe her "because it was Rolf Harris", and that she became "an empty vessel" after the alleged abuse.
"I was wondering why I was picked out of all those other people," she said.
She decided not to tell her "protective" mother, because she had pushed for permission to go on the trip.
Earlier, Ms Lee had told the court: "She was very hesitant to let me go. She had always been quite a protective mother."
She added: "I just convinced her that I'd be safe and I'd be in good hands."
Ms Lee claimed her ex-boyfriend encouraged her to sell her story about Harris's alleged sex attack - but said cashing in on the abuse was a "huge mistake".
She told jurors she finally plucked up the courage to tell police about the abuse last May after seeing a report in the Daily Telegraph which revealed Harris was being questioned by police on sex abuse allegations.
But she claimed she was quickly overwhelmed with the press and was encouraged by her then boyfriend, Fian McDaid, to enlist the help of Max Markson, a famous Australian celebrity publicist.
The mother-of-three eventually agreed to sell her story about the alleged abuse for 60,000 Australian dollars (£33,000) to a magazine and TV show - but claims she has only received 28,000 dollars (£15,400) herself.
Asked by Sasha Wass QC, prosecuting, whose idea it was to sell her story, she said: "Fian. Fian and Max."
Under cross-examination, she admitted telling police "a barefaced lie" by pretending not to be talking to the media, when in fact she was.
She choked up with tears as she told jurors that accepting cash for the story was a "huge mistake" she regrets.
But she said she was convinced to sell her story when she was holed up in a hotel.
She said: "Max had created this thing and I kind of went along with it. I felt like I was kind of trapped.
"I felt like I had made this agreement. I felt like absolute crap. I felt like I wanted to tell the truth. I was worried about the consequences with Fian. And I had been drinking - it is no excuse."
She insisted she was not putting all the blame on her ex-boyfriend and said she took "responsibility" for it. But she said she had been drawn in by the "charlatan" Mr Markson.
She added: "My biggest concern in all of this was that not, in a million years, did I ever think that I would get a chance to sit here in a courtroom in England and say what happened.
"The money is a huge regret, it is a huge mistake and I fully take responsibility for that.
"It was a huge whirlwind. Fian was in heaven thinking it was money and it was the answer to our prayers. And to me, money can't fix that."
She split up with Fian about a week after the story hit news stands and she gave him 10,000 dollars (£5,500) "in the hope he would back off somewhat, but unfortunately that wasn't the case".
The case continues.
Ms Lee said she had been inundated with requests for press interviews but had turned them all down.
She said: "The thing I regret the most about this is that if I hadn't had been so bombarded, so overwhelmed, and so pushed by other sources I would never have done it.
"My goal was to see if Scotland Yard would be able to help me."
She said she was shaken at the realisation of "how much I risked my opportunity to be here in this court today" by selling her story.
Ms Lee revealed she was plunged into decades of emotional turmoil by the abuse she claims to have suffered at Harris's hands.
She said she almost killed herself by taking a potentially lethal mix of dozens of laxatives a day while drinking heavily and half-starving herself because of her eating disorder.
She said: "I just thought 'I am killing myself. I was drinking. I felt really bad about all this bloody abuse.
"I had eating disorders and I was taking 80 laxatives a day for eight years and throwing up. Just hurting myself time and time again."
Ms Lee said she never thought she would get a chance to see Harris prosecuted in court for his alleged crimes.
Describing the Australian star as a "huge icon", she said she was worried no one would believe her because she was "a girl from Australia and it happened so long ago".
The case was adjourned until 10am tomorrow morning.