The feud started in January, 2006, when Eric Mangini told Bill Belichick he was leaving the Patriots’ kingdom to become the Jets’ head coach. The words had barely left Mangini’s lips when he discovered his security code to enter the Patriots’ facility had been cancelled. He wasn’t allowed to return to his office to retrieve personal belongings.

Thanks for the warm and fuzzy sendoff, boss.

Their relationship continued to deteriorate with skirmishes over free agents and assistant coaches, but the real friendship killer occurred in September, when the Jets busted the Patriots’ illegal spy ring. On opening day, they caught a sideline cameraman videotaping their defensive signals and notified the league, resulting in severe sanctions against Belichick and the Patriots.

Hence, “SpyGate.”

On Sunday, the two coaches and the two teams will meet for the first time since the cheating scandal, and you can expect a delicious mix of animosity, revenge and pride. It’ll be the ultimate reality show, in living color, staged at Gillette Stadium in Foxborough. Actually, it’ll be more like the Roman Colosseum, where the downtrodden Jets will be fed to the lions.

Come on, does anybody really think the Jets will beat the undefeated, history-seeking Patriots? The Jets are 2-0 against the winless Dolphins and 1-10 against the rest of the NFL. It would be one of the biggest upsets in the history of professional sports, considering the Jets are a 24-point underdog.

The Jets’ franchise lore is based on an upset, Joe Namath guaranteeing and delivering a win over the Colts in Super Bowl III, but this is an entirely different situation. For one thing, there are no Namaths on the Jets’ roster, only a bunch of ordinary Joes. The Patriots are a destructive force the likes of which the league has never seen. Anything less than a blowout would be considered a shock.

But isn’t that what makes this matchup so compelling? America loves a drama that includes hatred and blood, and there could be plenty of both Sunday. Will Belichick seek payback and try to embarrass his protégé-turned-adversary, Mangini? Does Tom Brady date pretty women?

Will Belichick run up the score? Will the Patriots hit 50 points? 60? 70? Will Belichick and Mangini shake hands after the game? This could be the most eagerly anticipated mismatch in football history.

“I guess from (the point spread) alone, we don’t have a chance, but that’s outside,” Jets safety Kerry Rhodes said. “In this locker room, we don’t feel that way. We feel we can play with anybody on any given day … It’ll be a competitive game.”

When the Jets blew the whistle on Belichick, it looked like the two teams would be legitimate competitors in the AFC East. The Jets, coming off a 10-6 season in which they split with the Patriots but lost to them in the wild-card round, thought they did enough in the offseason to close the gap on New England.

Pause here for laughter.

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After flicking aside the Jets on opening day, 38-14, the Patriots have blown away the league, winning by an average margin of 22 points. (The Jets average only 18 points per game.) Belichick, Brady and Randy Moss have been accused of running up scores, but as one former Jets assistant coach asks, “If you’re riding Secretariat, how do you pull in the reins?”

As for the Jets, they’ve been dreadful, undermined by poor quarterback play and an overall malaise on both sides of the ball. Privately, they might have enjoyed a temporary laugh at the expense of the Patriots, who were stripped of their 2008 first-round pick by commissioner Roger Goodell, but many believe Mangini received his comeuppance for ratting out his former boss.

In some circles, namely the New England region, Belichick has been cast as the victim, making him a martyr. That’s ridiculous. He blatantly and arrogantly broke the rules, defying repeated warnings from the league. Even though he’s a brilliant coach, he deserved the penalty (a $500,000 fine) and the embarrassment.

Even if Mangini did blow the whistle (Jets officials insist he wasn’t in on the sting operation), why would that have been such a bad thing? Was he supposed to remain quiet and let his primary division rival cheat in broad daylight in his own stadium? No one accused Belichick of disloyalty when he filed tampering charges against Mangini during the Deion Branch affair before the 2006 season, so why should the standards be different for “SpyGate”?

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Maybe that’s what makes this soap opera so juicy. Even though it shouldn’t be this way, the lines between good and evil are blurred. Who’s the protagonist? Who’s the antagonist? We pretty much know the ending. By 4 p.m. ET Sunday, the Patriots will be 14-0, one step closer to history — a tarnished place in history, according to former Dolphins coach Don Shula.

No doubt, Shula and the boys from ’72 would love to see Mangini kick Belichick’s asterisk.

So would a lot of people.