The former Beatle's first wife died of cancer in 1998 but during their 29-year marriage recorded 15 tapes of intimate revelations, which are now owned by her friend Paul Cox.
A source told Britain's Daily Mirror newspaper: "They're dynamite. Linda begins to unburden her troubles and the tapes become an audio diary."
"It's a private, emotional and confessional. She vents feelings which she'd not dared share with even her closest loved ones. She found the tapes cathartic."
Paul, 64, yesterday gained a legal undertaking that the tapes would remain secret after fears they would be used by his estranged wife Heather Mills as evidence in her divorce case, which is to be heard in open court.
The source said: "Mr. Cox has been silenced and the tapes remain a secret - for now."
Paul's management company MPL Communications threatened to take Paul Cox to the High Court unless he agreed in writing not to make the tapes public.
Sheridans law firm sent the threat to Mr. Cox's representative - London lawyer Rodney Hylton-Potts.
Sheridans demanded an undertaking, which was granted, not to disclose the contents of the tapes by 4 p.m. yesterday.
Paul is currently embroiled in a bitter divorce battle with ex-model Heather Mills, with both parties seeking divorce on the grounds of the other's unreasonable behavior after their four year marriage, which produced daughter, Beatrice, now three.
Paul was seen walking home from a London pub in the early hours of yesterday morning looking gaunt and exhausted.
The musician spent the evening drowning his sorrows with his daughter, fashion designer Stella, and her husband Alasdhair Willis.
