John Mara’s emotional meeting with Eli Manning in his office Wednesday should be a prelude to the next one they must have at the end of this godforsaken season.

And the next one should be a tearful Manning telling a tearful Mara that he is ready to finish his career elsewhere, and a tearful Mara embracing him and vowing he will do right by him and trade him to a team that is closer to a championship than the Giants will be.

Because the Giants co-owner was on board with the decision to take the gut-wrenching step towards Life After Eli Manning.

Mara revealed that over a week ago he had told general manager Jerry Reese: “Don’t you think it’s time that we start to get a look at these other quarterbacks at some point during the games?”

That’s when the Giants finally became the heavy-handed team Ben McAdoo has promised.

McAdoo’s plan to play Manning for a half before sitting him for Geno Smith was nothing short of half-baked.

“I didn’t necessarily think it had to be at the half,” Mara said. “I think if he’s playing well in the first half, we’re winning the game, it looks like we got a chance, the offense is clicking, I would argue that you keep him in the game.”

Coach Mara might have gotten it right.

Coach McAdoo did not.

“It was presented the way that Ben thought it ought to be presented,” Mara said. “Could we have done it differently? I guess you could argue that we could have, yes.

“The point was we did not want him on the bench, we wanted him to start the game and play some portion of the game and at some point, work the other guys in.”

Regrets? Mara had a few.

He was surprised by the public outrage, from within the Big Blue family and outside it. More surprisingly, he was surprised by Manning’s reaction to the most painful sack of his life. He should not have been. The guy just started 210 consecutive games! He understood better only after his sit-down with Manning.

“The timing of it could have been a little different, I wish I could have been here when that was all going down,” said Mara, who was attending the owners meetings in Manhattan, “but what I did not expect — and this is my fault, I was probably naïve — I did not expect Eli to react by saying, ‘Go ahead and start the other guys.’ ”

Parting is such sweet sorrow.

The Giants will be drafting their next franchise quarterback in April, and in a perfect world, Manning would be the starter and mentor until such time as the kid is ready to take the torch from him.

Except there will likely be a new GM and a new head coach who might not want Manning to start so much as the first half of the first game of their first season together.

“We’re 2-9. I’m embarrassed about that. Nobody’s doing a good job,” Mara said.

Asked if he could guarantee that McAdoo’s job was secure for the rest of the season, Mara said: “There are no guarantees in life.”

Manning wants one more shot at a third Super Bowl championship, and this is no longer the place for him. Tom Coughlin’s Jaguars qualify.

Manning did not discuss waiving his no-trade clause with Mara. Asked if Manning expressed a desire to play somewhere else, Mara said: “No.”

He should.

“Obviously we’re going to have a high draft pick this year and there are going to be some quarterbacks available, so that’s going to be a decision that we’re going to have to make,” Mara said, “but I’d like to make that decision at least having watched some of these guys play.”

Tanks for the memories, Eli?

“I read something somewhere about, ‘Are we gonna tank the rest of the season?’ That’s complete bulls–t. I would never allow that,” Mara said.

Manning will be 37 years old in 34 days.

“I think he can still win in the NFL, yes, and I hope it’s here,” Mara said, “but that’ll be a discussion for the offseason.”

Manning ran the scout team at practice Wednesday. “It was weird,” Orleans Darkwa said. Manning put on a brave face with his shell-shocked teammates, never stopped being the consummate pro through all the hurt inside.

Yes, the NFL is a cutthroat business, and every franchise confronts these crossroad moments with an icon.

But this was the wrong time and the wrong way to cut Eli Manning’s throat.

He wasn’t only Peyton Manning’s Little Brother.

He became New York’s Little Brother.

We watched him grow up into a man.

A SuperMann.

Giant For Life? Till death do they part? Sorry. The marriage is over.

No one deserves an amicable divorce more.