MACKENZIE DIDN'T TELL ALL

What you WON'T read in Mackenzie Phillips' new tell-all but ONLY in The ENQUIRER!

Former One Day at a Time star Mackenzie Phillips was married at 19, and just weeks later her husband offered her up as a sex toy to a friend!

That revelation is NOT included in Mackenzie's new book High on Arrival which made headlines with the shocking claim that she had a 10-year incestuous affair with her father, The Mamas and the Papas legend John Phillips.

Mackenzie married Jeff Sessler, a gofer for the Rolling Stones, in August 1979. The marriage lasted seven months.

Mackenzie says in her book that her father had sex with her for the first time shortly before she married Sessler. She says her sexual relationship with her dad eventually became consensual.

Rick Breitstein, a good friend of Sessler, told The ENQUIRER he was on his honeymoon in Los Angeles in September 1979 and hooked up with Sessler and Mackenzie.

After a visit to the set of  One Day at a Time, Breitstein, his wife and other friends went back to the hotel where Sessler and Mackenzie were staying.

"We did cocaine and Quaaludes all night," Breitstein recalls.

"At that time, Mackenzie was getting in trouble with the show for her drug use and was saying how she had to hide her cocaine.

"She had this fake fountain pen which she could put cocaine in and that's how she was snorting it that night. We'd do cocaine for a while, then Quaaludes, then more cocaine."

At one point, Breitstein said he was in the upstairs bedroom of the two-story hotel suite with Sessler.

"He came right out and said, 'Do you want to swap wives tonight?' He was absolutely serious!"

Breitstein, on his own honeymoon, says he rejected the idea.

"Mackenzie and Jeff had been married only a few weeks before," said Breitstein, now 58, who owns The Cheese Shop in Ridgewood, N.J.

"I don't think Jeff really loved her."