Ages before “Jen” and “Brad” very publicly fractured amid “Brangelina,” the high bar was set on salacious Hollywood sex scandals by Debbie and Liz and Eddie.

“Debbie” was Debbie Reynolds, the fresh-faced, 1950s Girl Next Door, young mom to an infant son and a 23-month-old girl named Carrie Fisher.

“Liz” was Elizabeth Taylor, the violet-eyed star whose negligee-clad image hung in movie theaters across the country as the promo poster for her just-out movie, “Cat on a Hot Tin Roof.”

And “Eddie” was Eddie Fisher, the pop crooner and teen heartthrob who had leaped from the tidy marital bed he had shared with Debbie and right onto the very hot tin of Taylor’s roof.

When news broke in September 1958 that Elizabeth Taylor had stolen Eddie Fisher from Debbie Reynolds, the tabloids exploded.

Three of the world’s biggest stars had collided in the most spectacular and most public manner.

Reporters camped out on their lawns; once, during a failed attempt at reconciliation, Fisher and Reynolds sneaked out their Los Angeles back door and clambered over the neighbor’s fence to escape the press.

“You ought to know better!” spies claimed to have heard a red-faced Reynolds hectoring her philandering hubby.

“It doesn’t look good to have stories like this in the papers! . . . What’s the matter with you, anyway?”

“All that publicity and scandal,” Reynolds later recalled to The Post in a 1973 interview. “It was very hard for me to suffer that kind of humiliation.”

Carrie Fisher described it this way in her 2008 memoir, “Wishful Drinking”:

“Now if you are too young to relate to any of this, try and think of it this way: Think of Eddie as Brad Pitt and Debbie as Jennifer Aniston and Elizabeth as Angelina Jolie. Does that help?”

Unlike with Aniston and Jolie, our two leading ladies, Reynolds and Taylor, had been best friends when betrayal struck, despite their screwball-comedy-worthy differences.

In the 1950s, Reynolds was America’s Sweetheart — all tap shoes and modest necklines and “Oh, what a lovely morning!”

Taylor, meanwhile, was America’s Seductress — heels, cleavage and, as she declared as a hooker with a heart of lead in “Butterfield 8”: “Face it, Mama. I was the slut of all time!”

Taylor was never a Girl Scout. And she did not tap dance.

Both stars were teens when their friendship began.

“I went to MGM when I was around 17, and Liz was there, too, but she was already a star,” Reynolds told People magazine last year.

“We went to school together on the lot, when she was in between films. I was just a beginner, and she and I were not in any manner alike, but we got along very well because I was in awe of going to school with Elizabeth Taylor.”

The two BFFs even wound up marrying best friends.

Fisher was great pals with Taylor’s third husband — dashing, Oscars-winning film producer Mike Todd. When Taylor and Todd married, Fisher was best man and Reynolds was matron of honor. Carrie’s little brother, Todd, bears the producer’s surname.

The two Hollywood power couples vacationed together in exotic locations; the Todd-Taylors, in particular, were “divinely in love,” as Reynolds wrote in her 1989 memoir, “My Life.”

Then one morning in March 1958, “Frank, our Mexican houseman — came rushing in” to the Fishers’ New York apartment.

“It’s Mr. Todd! He was killed in a plane crash!”

Reynolds’ first thought, she wrote in the memoir, was for Taylor.

“Elizabeth! I thought, she’s going to be destroyed.”

She urged her husband, himself grief-stricken, to rush to Elizabeth’s side. As Todd’s best friend, who better to console the new widow?

Reynolds had barely ever been kissed when she married Fisher in September 1955.

(Well, except for that day on the set of “Singin’ in the Rain,” when, at age 19, she puckered up for her first-ever on- or off-stage kiss. A mischievous Gene Kelly unexpectedly French-kissed her, leaving her spitting and shrieking, and the director shouting, “Cut!”)

“Needless to say, I was a virgin when I married,” Reynolds told The Post in 1975.

“Like my mother before me and her mother before her,” she said.

Fisher was a “big-name singer” when Reynolds met him at age 22, she said.

“He asked me to marry him on our third date,” she said. “Then about a month later, he gave me the biggest diamond ring I’d ever seen in the history of the world, something like 11 carats.”

Fisher had hid the emerald-cut sparkler in a crumpled-up piece of Kleenex before handing it to her.

Before that, “the extent of my jewelry was a little tiny gold watch that I’d bought and was paying $48 a month for.”

They were engaged — all the while remaining chaste — for a year before their wedding night.

“He did not mishandle a young girl of inexperience,” she winked to The Post of her far-more-experienced new groom.

Fisher gave her a toy poodle named Rocky and often called his new bride, fondly, by her given name, “Mary Frances.”

The press called them “America’s Favorite Couple,” although as months passed, Fisher proved a distant, distracted husband.

Then, two years and two children into their marriage, Todd’s plane, the Lucky Liz, crashed over New Mexico.

Todd was 48; his glamorous, weeping widow was just 25; their one-year marriage had produced an infant daughter, Liza.

“Elizabeth was in shock and pain,” Reynolds recalled in her 1989 memoir.

Taylor had been filming “Cat on a Hot Tin Roof” in Hollywood, and the newspapers filled with stories of production delays, and of the star being confined to her Hollywood home under doctors’ orders, woozy on sedatives.

“Why? Why?” the hysterical new widow asked a steady stream of visitors, The Post reported in April 1958.

“How did it happen to my Mike?”

The most frequent of those visitors was Eddie Fisher.

“He consoled her with flowers,” Carrie Fisher would quip in “Wishful Drinking,” “and ultimately, he consoled her with his penis.”

Haunted by rumors and her own intuition, Reynolds in August 1958 tricked her husband into confessing the affair.

“Elizabeth, I figured, was at The Plaza,” in Manhattan, with Fisher, Reynolds wrote in her ’89 memoir.

‘I thought of killing myself.’

“I placed the call and told the switchboard operator, ‘Mr. Dean Martin calling from Beverly Hills,’ ” sounding like somebody’s secretary.

“Fifteen seconds later, Eddie picked up the phone. ‘Well, hiya, Dean, whatcha doin’ calling me at this time of night?’ ”

Reynolds told him: “Just roll over, Eddie. I want to talk to Elizabeth.”

“I heard her say, ‘Who is it, darling?’ ”

“I thought of killing myself,” Reynolds told The Post in 1973 of Fisher leaving her.

“I tried. I just took thousands of pills, you know?”

Ultimately, she decided she couldn’t bear to leave her two children.

What comes around goes around: Liz took Eddie from Debbie, but very soon, actor Richard Burton took Liz from Eddie.

Fisher became the butt of jokes for stand-up comics and descended into gambling, drugs and bitter memoir-writing.

The two old high school pals, meanwhile, went on to continue their stage and screen success, and let bygones be bygones.

They made up soon after Taylor threw Fisher over. “Elizabeth and I went on a cruise ship, and we were on the same boat . . . She sent a note to me and I sent a note to her to say, ‘Let’s just forget about it,’ ” Reynolds told “Access Hollywood” in 2013.

They were pals for decades. And when Liz died in 2011 at age 79, she recalled Debbie in her will — leaving her a case full of sapphire jewelry.

And Reynolds eulogized Taylor warmly.

“No one else could equal Elizabeth’s beauty and sexuality,” she said without a note of bitterness. “Women liked her and men adored her — my husband included.”