Laurie Asher, 17, told a trial she was attacked in a lay-by near a deserted country road by leisure centre worker Michael Willis, 24, who was wearing latex gloves at the time.
Mr Willis, of South Queensferry, denies a charge of attempting to murder the girl on June 21 last year, when she was only 16.
It is alleged that on the outskirts of South Queensferry he repeatedly placed his hands over her mouth and nose, restricting her breathing, then dragged her from his car, throwing her into bushes where he sat astride her and put his hands round her neck until she passed out.
The High Court in Edinburgh heard married Mr Willis and Ms Asher had a boyfriend-girlfriend relationship during the months before the alleged murder attempt.
The trial also saw hundreds of text messages sent to Mr Willis by Ms Asher threatening to tell his wife, employers and police about the affair.
Questioned by solicitor advocate Ray McMenamin, defending, Ms Asher admitted she was annoyed because Mr Willis was ignoring her but insisted she would not have carried out the threats.
Giving evidence from behind a screen, she said Mr Willis agreed to take her for a drive and they pulled up in a lay-by off the Kirkliston road.
The court heard that Mr Willis made as if to kiss her but grabbed he and then got out of the driver's seat, walked round and pulled her out of the car.
Ms Asher said she was scared when Mr Willis pushed her into bushes and sat on her knees. "He was suffocating me. He was wearing gloves, clear latex ones."
She said she begged him to let go, but Willis said: "No, you will tell people."
The trial continues.