He was a spoiled fella.

John “Junior” Gotti was a “self-mutilating” stunad with no street cred, according to his former best friend and mob turncoat John Alite.

“He’s like Kim Jong-un — a spoiled brat that took advantage of guys around us by his dad’s authority,” the former Gambino crime-family enforcer seethed to The Post.

“Ever since we were kids, he’s self-mutilating himself, burning himself with cigars,” Alite said in his first interview before a book by George Anastasia — “Gotti’s Rules: The Story of John Alite, Junior Gotti, and the Demise of the American Mafia” (Dey St. Books) — hits shelves on Jan. 27.

“He would play drinking games with other guys, and part of these drinking games was if you lose, you gotta burn your hands with cigars,” he continued. “These are his ideas.

“This is what made Junior an inadequate boss: his insecurities,” Alite said of the Mafia scion who was always trying, and failing, to prove his toughness to the true tough guys around him.

“He forgot about me and guys like me standing in front of him if ever someone raised their hands to him,” said Alite, 52.

Junior was 28 when he inherited the helm of the nation’s most powerful crime family in 1992 as his father, the “Teflon Don” John Gotti, went to the slammer. (He remained acting boss until at least 1999, when, Junior claims, he quit the mob.)

In the eyes of Alite and other Gambino “earners,” the new boss was thick as a slice of Sicilian pizza and about as tough as overcooked fettuccine. He was branded with insulting nicknames such as “Urkel” — for wearing chest-high sweatpants like the TV nerd — and “Kong” — because some thought he looked like an ape. Even his own sister, Victoria, had a moniker for Junior — “Blinkie,” because he blinked incessantly when he lied, which was often.

Alite’s biggest beef was his pal’s penchant for “blaming anyone close to him when something goes down.” He recalled how Junior and several members of his crew got into a scrap at a Queens club.

“From behind me, Junior pulls out this derringer, reaches around my body and shoots the kid. A cheap shot,” Alite says in the book.

Turned out the victim, who was hit in the thigh, was the nephew of Genovese capo Ciro Perrone — creating a major headache for John Gotti Sr.

The don demanded to know who the triggerman was, but Junior never confessed. Instead, he let Alite take the fall — and catch a beating for it.

“The father was a tyrant and the son was a p—y . . . that’s what people don’t know about the Gottis,” Alite says in the book.

Junior was also no Einstein. The book notes how, in 1997, Gotti Jr. was caught red-handed by the feds — twice — with documents that hurt the five families.

First was a bookkeeping ledger in an Ozone Park apartment found alongside about $350,000, listing all of Junior’s wedding guests and what they gave — a veritable who’s who of the American mob.

“Junior kept cash in that basement, and what he would do was continually replenish the supply. Money he made from drugs, gambling, extortions, whatever wound up in that basement. That’s why the cash they found amounted to about the same total as the money in the ledger,” Alite says in the book.

Second was a secret list of candidates to become “made men” that year, which the five families would circulate to weed out problematic nominees. The standard practice was to destroy the lists — but Junior decided to save his as a keepsake, enraging the other families.

His reign ended the next year when he was arrested and charged in a racketeering indictment — which clued the families in to the embarrassing details.

Alite, a Woodhaven-born Albanian whose father drove a cab, took the stand against his pal in 2009 for the feds’ fourth and final attempt to send the mob scion to prison on racketeering and murder charges. The hung jury would later say they found Alite’s testimony less than credible, but the tough guy — who from 1996 to 2014 spent 14 years in prisons on charges and convictions that included six murders, at least 37 shootings, home invasions and countless beatdowns — is still chirping.

Alite describes how he was running with Junior by 1983, and thanks to drug, bookmaking and loan-shark operations, was living large. Some months he alone would pull in $100,000, he said.

He was so close to the Gottis that he’d crash on the couch in their two-story house in Howard Beach — where it was rarely a quiet night.

“He overheard shouting matches in which [Junior’s mother] Victoria matched her husband expletive for expletive,” the book says.

Alite also learned the secrets of the mob clan. For example, despite his nickname as the “Dapper Don,” Junior’s father was a “terrible dresser,” who, left to his own devices, would look like the Steve Martin character in the “Wild and Crazy Guy” skits on “Saturday Night Live.” When Gotti Sr. became boss, he had an associate named “Fat Bob” serve as his stylist — Gotti had the money for the $2,000 outfits, “he just didn’t have the fashion sense to put it together.”

Junior sometimes did the right thing, Alite said. The night before Alite was going to prison on an assault charge in 1991, Junior threw a party in Alite’s honor. They had a cake in the shape of an inmate, with frosting that read, “It’s up the river for you John.” “He told all the guys to make sure they bring money I was owed every week to my wife,” Alite recalled. “It was a substantial amount.”

But it was Alite’s alleged relationship with Junior’s sister, Victoria — a relationship she denies — that marked the beginning of a rift between Alite and Junior.

“I was fooling around with Vicki Gotti on the sneak, nobody knew, in the late ’80s,” he testified in 2009 at the trial of hit man Charles Carneglia. “I had a problem with Carmine beating up Vicki. That turned into me, Vicki fooling around a lot, seeking each other on the sneak.”

These days, Alite is tight-lipped about the fling. “We were kids at the time — I have a lot of respect for her, but I wasn’t going to lie on the stand.”

Junior faced four racketeering trials and walked each time after juries failed to reach a verdict.

In advance of Anastasia’s book, Junior rushed out a self-published memoir last week called “Shadow of My Father,” in which he for the first time acknowledges his leadership role inside the Gambino family — but says his father was the one ordering hits.

Alite, a free man since 2012, now lives in Freehold, NJ, and said he can’t remember the last time he served up a knuckle sandwich. For the past two years, he said, he’s going to therapy and working in real estate, overseeing the rehab of distressed homes. “I’m struggling a bit, but it’s a job.”

For better and worse, his old life as a coldblooded murderer still haunts him. “You miss hanging out with everybody and laughing, but you don’t need to be a mobster to do that.”