There are backbreaking games and heartbreaking games, losses that stay with teams so long they come to define them.

In a first half of a season chock full of such defeats, the Knicks might have saved their worst for last.

A 28-point lead became a stunner of a loss in their final game before the All-Star break, a crusher in which Kevin Durant — who did not even play in the Nets’ 111-106 win — was ushering the Knicks out of the Garden on Wednesday night.

Durant was waving and celebrating with the rejuvenated Nets, who though bereft of their stars, have won two straight following 11 straight losses and plenty of James Harden drama.

The Knicks were shocked, even if that feeling seems to be habitual now.

Following their third loss in seven games in which they had held at least a 20-point lead (becoming the first team to watch that many huge leads disappear in the same month in the last 25 seasons, according to ESPN) the Knicks trudged off the court to questions about what comes next for a team that was the Eastern Conference’s No. 4 seed last year, but now is spiraling out of even the play-in conversation.

The top question involves coach Tom Thibodeau. He continues to have no answers and presides over a team that was outhustled late. He also bungled a Knicks challenge in their previous devastating defeat, an overtime loss to the Thunder on Monday.

Thibodeau dodged a query about his job security, but sounded open to making just about any change he could following the break.

“The thing is all I think about is winning. I don’t care about any other nonsense, I just care about winning. That’s it,” Thiobodeau said after the Knicks (26-33) fell 3 ¹/₂ games behind the Hawks for the last play-in spot. “Everything’s on the table now, it has to be.”

The Knicks led by 20 after a quarter and ballooned their lead to 28 with 6:44 left in the second, before the Nets started chipping away. The Nets, who still trailed by 18 less than a minute into the fourth quarter, went on a 15-0 run in a little over four minutes to take a two-point lead, 99-97, with 3:58 left after Cam Thomas hit back-to-back step-back jumpers.

The biggest possession began with the Nets leading, 106-103, and 49.9 seconds left. LaMarcus Aldridge bricked a jumper before Patty Mills missed a 3-pointer, but the Nets hunted down each rebound and eventually called timeout with 16 seconds remaining.

“Couldn’t get a stop,” said Julius Randle, who exploded for 20 first-half points, but disappeared in the second, finishing with 31 points and 10 rebounds. “Simple as that.”

The Knicks were outhustled, and then they were beaten. Thomas, who finished with 21 points on 9-for-21 shooting, drilled a step-back 3-pointer with 7.7 seconds left to clinch the victory and humiliate the home team, whose fans headed for the exits.

The Nets had no Durant (knee), Ben Simmons (working his way into shape), Kyrie Irving (unvaccinated) or Joe Harris (foot). It didn’t matter.

“Nets fans were loud in the barc….I mean the garden tonight,” Durant tweeted after the game.

The Nets again got big contributions from the players it received from the 76ers in the Harden trade. Seth Curry had 20 points on 6-for-9 shooting from beyond the arc, and the 6-foot-10, 279-pound Andre Drummond was enormous in his second game since the trade, grabbing 19 rebounds and adding 11 points.

After beating the Kings on Monday, the Nets credited a locker room in which “everybody likes everybody,” following the trade deadline deal that sent Harden to Philadelphia. Camaraderie certainly helps, though perhaps not as much as Simmons’ Nets debut and Durant’s return will.

There has been a decreasing amount of hope around the Knicks all season. They had no RJ Barrett (ankle), Nerlens Noel (foot) or Derrick Rose (ankle), yet still jumped out to a huge lead on the backs of their 3-point shooting and Randle.

By the end, forgotten were the Knicks’ eight first-quarter 3-pointers and the bounce-back game from Immanuel Quickley (7-for-10 shooting for 18 points). In the fourth quarter, “nothing good” happened, Randle said.

Randle and Taj Gibson both stood up for their head coach, saying the Knicks are still listening to Thibodeau’s message. But his message rarely involves losing every 50-50 ball.

“This is an opportunity for people,” said Thibodeau, referring to a wide-open race for playing time when the Knicks return from the break.

The next question will become: Will there be an opportunity for another coach?