Convicted double-murderer SCOTT PETERSON’s appeal for a retrial sparks terror for AMBER FRY – the mistress whose evidence helped send him to death row.

Ironically, the shocking develop­ment comes just months after the blonde masseuse finally felt strong enough to tell her 11-year-old daughter Ayiana about her starring role in one of America’s most sensa­tional murder trials.

“Just when Amber thought the terrible ordeal was finally behind her, Scott is going to make her live it all over again,” her father Ron Frey told The ENQUIRER in an exclusive interview.

It was seven years ago that Peterson, now 39, was sentenced to death for the Christmas Eve murder of his wife Laci and their unborn baby son Conner. Amber, now 37, had fallen in love with the cheating husband after he posed as a widower, telling her he’d “lost” his wife – two weeks before Laci’s actual disappearance from the couple’s Modesto, Calif., home.

Scott pretended to be baffled by her disappearance, and as the hunt for Laci made worldwide headlines, Amber bravely came forward to help. In the weeks before the bod­ies of Laci and Conner washed up on the shores of San Francisco Bay, Amber allowed cops to tape phone conversations she had with Scott, which would later help jurors con­vict him.

Scott’s desire to be with Amber was a key motive in the killings, said prosecutors at the trial.

“Amber was hurt and devas­tated by Scott’s betrayal, and she’s never recovered,” her dad told The ENQUIRER. “Now she’s going to be back in the spotlight again, and what makes it worse is that her two children are now old enough to understand. She had the toughest task a mother can imagine just last year when she finally felt able to ex­plain to Ayiana how she was duped by a murderer.”

And with the case back in the news, it’s going to be even more difficult, say friends, when her 8-year-old son Justin faces questions from pals at school about his mom’s role.

Amber does talk about her relationship with Scott on the Investigation Discovery channel’s “Who the (Bleep) Did I Marry?” – set to air in August – but that’s a lot less traumatic than a new trial would be, according to her father.

“There’s’ a hell of a difference between ap­pearing on a TV show about bad dates, in which she is in control, and possibly having to face Scott in court again and un­dergo grilling by his lawyers,” Frey explained.

Since March 2005, Scott has been on death row at the notorious San Quentin prison, overlooking the bay where the bodies of Laci and Conner were found.

Emotionally shattered, Amber underwent counseling after the trial and married a year later. But the couple split and she’s been a single mom juggling her children and her massage business for the last few years.

Her father told The ENQUIRER there’s only one possi­ble bright spot in Scott’s bid for a new trial.

“Maybe we will final­ly learn the truth about how and when Laci died