ATLANTA — And so, 2 hours and 58 minutes after they clinched their playoff berth, the Mets finally got to celebrate. With goggles over their eyes and cigars in their mouths, the Mets popped corks of Freixenet prosecco and doused each other in Coors Light. They had done what was unexpected entering the season and unfathomable early in it.

Advertisement As they stopped each other for selfies, president of baseball operations David Stearns stood in the back, his dress shirt already drenched through. “This is where we should be,” Stearns said. “This is the standard.

” The Mets have played baseball for 63 seasons and nearly 10,000 regular-season games. The best of them was Monday afternoon. “The best I’ve ever played in,” said José Iglesias , the 12-year veteran.

“That was real baseball.” “Honestly?” said Mark Vientos . “I felt like I was on a roller coaster.

” “That was one of the craziest games I’ve ever been a part of,” manager Carlos Mendoza said. “Like, you could write a book.” If ever nine innings could recapitulate the twists and turns of this 162-game Mets season, New York’s 8-7 win over Atlanta in the opener of Monday’s doubleheader pulled it off.

An early deficit, a rollicking comeback, a near collapse and ultimate redemption — the Mets stuffed eight months of drama into two innings of baseball. You will see it on SNY every time it rains for the next decade. New York scored six times in the top of the eighth to turn a three-run.