Words may fail to encapsulate all the ways life went wrong for the Mets Thursday, a day when it seemed they had offended baseball itself, and now baseball was back to take its vengeance.

But we’ll try.

It was, first off, the 40th anniversary of the “Midnight Massacre,” that woeful day in Mets history when they traded The Franchise, Tom Seaver, and snakebit the franchise. It was the day they placed Neil Walker on the disabled list with a partially torn hamstring. The day Matt Harvey was diagnosed with a scapula strain that will cost him several weeks. Juan Lagares left in the fifth inning with a fractured joint in his left thumb. Starting pitcher Robert Gsellman imploded.

Oh, and did we mention that the Nationals were in town?

Or that Daniel Murphy hasn’t changed a lick when it comes to facing his old team, and that Citi Field still feels like home to Gio Gonzalez? Murphy went 3-for-5 with two RBIs, and Gonzalez (6-1) pitched seven innings of two-run ball, adding an RBI in an 8-3 win over the Mets.

It was, in short, the type of day that the Mets will try valiantly to forget, as hard as it may be. After winning five of their previous six, things certainly looked to be trending in the right direction, but a tsunami of bad news has tempered expectations.

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“That’s kind of my thought: How many can we possibly continue to have to play through?” Terry Collins said. “But you know what the answer is? As many as pop up. That’s as many as you have to play through.

“I’ll say this will be the last time and then tomorrow, somebody else goes down. We just got to play through them. We can’t sit there with our bottom lip out and mope about it.”

Gsellman, who had been brilliant recently, struggled from the outset. With two outs in the first, his 3-and-1 sinker remained on a tantalizing plane for Bryce Harper, who did exactly what Bryce Harper does to pitches that don’t do what they ought. His shot to right traveled nearly 400 feet to put the Nationals up 1-0. It was his 10th career home run at Citi.

That, in itself, was no great tragedy, but it portended more to come: The Nationals regularly elevated the ball against a pitcher whose strength lies in his sinker. Gsellman allowed seven earned runs and 11 hits over five innings.

The big blow came in the five-run fifth, helped along by Murphy’s two-run triple. As if mocking the Mets, Murphy’s ball there ducked under Lucas Duda’s glove and trickled to the corner in right, where Jay Bruce couldn’t quite corral it. It put the Nationals up 5-1. One play later, Anthony Rendon hit a blooper that eluded Lagares, who smashed his thumb diving headfirst for it.

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Michael A. Taylor hit a two-run home run one batter later to put the Nationals up 7-1. “I can’t take it back now,” said Gsellman, generally a man of few words, but more so last night.

It was the first loss for Gsellman (5-4, 5.50 ERA) since May 13, and his first since returning from the bullpen four starts prior. He had won three straight, pitching to a 1.42 ERA, before this no good, very bad Thursday.

Rene Rivera and Wilmer Flores hit solo homers for the final margin.

“We need to move forward,” said Curtis Granderson, who came in for Lagares. “We’ll find a way to keep moving forward. We’ve still got to play tomorrow no matter who we happen [to have] out there, and we have to go out there and fight.”

It just so happens, the fight just got a whole lot harder.