Andy Kaufman's Last GF He's Dead Dead Dead Dead ... I Watched Him Die

11/15/2013 1:00 AM PST

Andy Kaufman
is dead as a doornail and he's NOT coming back, so says his last girlfriend -- who tells TMZ, she watched him die ... and the self-proclaimed "daughter" who revealed herself this week is a big fat phony.

56-year-old Lynne Margulies tells us, she was present inside the West Hollywood hospital room when Kaufman passed away in 1984 from a rare form of lung cancer. She was there, and she insists she saw him die with her own eyes.

She says, "I was in the hospital room. I was there. They would have had to switch bodies."

Lynne is convinced the 24-year-old woman who claimed she was Kaufman's daughter this week at the Gotham Comedy Club is just "pulling an Andy" and trying to perpetuate the myth that the comic's still alive.

Lynne believes Andy's brother Michael -- who was hosting the 9th Annual Andy Kaufman Awards when the mystery woman stepped forward -- is in on it too.

Lynne says she knows Andy's REAL daughter Maria, who's in her 40s, and insists Andy has no other children.

If that's not enough, we've also obtained Andy's official L.A. County death record, which lists his date of death as May 16, 1984.

So now we'll ask again ...