Pressure of reliving son Jett's death too much for superstar John Travolta.

John Travolta suffered a devastating emotional collapse as he prepared to relive the tragic death of his beloved son Jett in a courtroom, The ENQUIRER has learned exclusively.

The Saturday Night Fever star was stricken on the eve of the trial of two conspirators who allegedly tried to blackmail him for $25 million while he and wife Kelly Preston were in the depths of mourning.

Travolta, 55, was determined to give evidence that would force him to recall the agony of the unsuccessful fight to save the life of his 16-year-old autistic son.

But the approach of his scheduled appearance at the trial in Nassau, Bahamas, that began on Sept. 21 took a terrible toll on the star, say sources.

"The worry over giving evidence had been eating away at John for months," an insider told The ENQUIRER.

"Just the thought of going back to the country where he and Kelly lost Jett and having to live through that nightmare again became too much for him.

"He was truly panicked by the idea of having to go on the witness stand and recall the battle for Jett's life."

After publicly admitting Jett was autistic for the first time after his one day of testimony on the stand, Travolta won't take the stand again until next week.

For all the details of Jett's death, the blackmail plot and the next step in Travolta Family's recovery from their devastating loss, pick up the new ENQUIRER.