The Islanders lost to the Rangers in overtime, 6-5, in the NHL Stadium Series on Sunday at MetLife Stadium. Credit: Newsday/Heather McGowan

We are going to need to take this in multiple stages after a head-spinning Sunday afternoon at MetLife Stadium, folks.

Deep breath .  .  . OK, let’s go.

Point No. 1: It was a great day for hockey in general and New York-area hockey in particular as the Rangers and Islanders followed up Saturday night’s Devils-Flyers show with an even better one.

The NHL Stadium Series finale was a 6-5 comeback victory in overtime for the Rangers before a crowd of 79,690 and an atmosphere that received rave reviews.

Pat yourselves on the back, fans, players and those who organized the event. Bravo!

Point No. 2: The Rangers are good. Really good. The victory was their seventh in a row, and they seem to have as good a chance as any team to play deep into June.

Their fans showed up in force at MetLife, filling about two-thirds of the place, and those who stuck around for the big finish went home chilled but thrilled.

See you this spring, guys. Should be fun.

Point No. 3: This is the one on which we will be spending the rest of our time here, because hot messes usually are more interesting than hot teams.

How the heck do the Islanders bounce back from this?

It is theoretically possible, of course. But when it was over, the Islanders did not even have the energy to deny the obvious — that this was no ordinary loss.

Playing their biggest rival for the first time in 14 months before the largest crowd to see the team play in person, they blew a three-goal lead, led by two with less than five minutes left, allowed two late power-play goals with the Rangers’ net empty, then lost 10 seconds into overtime on a giveaway by one of their top defensemen.

To their credit, the Islanders were not interested in hearing about salvaging one point.

“I mean, [expletive], that doesn’t matter,” said Mathew Barzal, whose late penalty set up the Rangers’ fourth goal. “It was a big game, big atmosphere.

“Whether it’s a point or no point, sure it’s nice in the standings, but tonight was a big game. It was emotional. So it sucks not to get two.”

Said Casey Cizikas: “It was a massive game for us as a group, and I thought we played a really good game. I thought we took it to them for 50, 55 minutes.

“We just couldn’t get it done in the end .  .  . It was a great atmosphere to be a part of it and a great game to be a part of. Just a tough way to finish it.”

The saddest and truest words might have been Brock Nelson’s: “This one feels like it’s going to take a little bit right now, just given the circumstances of the day and the game and environment.

“[We’ll] take a little bit of time now to just reflect and finish this day off and review tomorrow and think about some areas where we can tidy up.”

It feels more like the Islanders need a gut renovation than tidying up after what went down at MetLife, a place that has had its share of Jets and Giants meltdowns in the past 14 seasons and now has a hockey collapse to call its own.

They let down the outnumbered Islanders fans who cheered for them all day and an organization that was celebrating the news that UBS Arena will host All-Star Weekend in 2026.

They tarnished a day on which they arrived in style, accompanied by blaring fire engines from East Meadow, Elmont, Commack and Greenlawn.

Islanders great Denis Potvin said on ABC that it was the best hockey environment he ever had experienced. Then he broke the news about the All-Star Game.

It was a great day to be an Islander. Then suddenly it wasn’t.

“Obviously, when you have a two- or three-goal lead like we did, you have to find a way to get the two points and get the job done,” said Noah Dobson, whose turnover set up Artemi Panarin’s game-winner.

Barzal’s penalty was followed by Scott Mayfield’s third — third! — minor penalty of the day, which led to Mika Zibanejad’s tying goal at 18:31.

Apparently, the Islanders’ four consecutive days of practice this past week under still-new coach Patrick Roy did not solve their problems.

“They made their power plays count,” Cizikas said. “As a [penalty] killer, it’s tough. We take a lot of pride in what we do. Just have to get the job done.”

Remember that before the game, the asterisk to the excitement over the event was that this was a huge game for the Islanders no matter the venue.

They are four points out of a wild-card playoff spot and certainly still in it mathematically. But the Islanders were not thinking about math Sunday evening as much as psychology, and about how to avoid flunking.

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