Now we know why Notre Dame’s football hero Manti Te’o played so poorly against Alabama in the national championship game Jan. 7.

His heart was broken, kind of, by a woman who didn’t exist.

It was all in Deadspin, an Internet sports blog, on Wednesday, about an amazing sports hoax, a hoax that was spread witlessly by sports writers peddling the heart-wrenching tale of the heroic linebacker, his dying girlfriend and the true love they shared.

They probably forgot the ancient credo of the City News Bureau of Chicago:

When your girlfriend dying of leukemia after suffering a car crash tells you she loves you — even if it might help you win the Heisman Trophy — you check it out.

Actually, the City News Bureau credo goes like this: If your mother tells you she loves you, check it out. My wife hates that credo. All mothers do. But reporters should love it.

Te’o’s “girlfriend” Lennay Kekua didn’t exist. He never met her. And even though the saga was the centerpiece of the Notre Dame football storyline, almost like that cool speech the Gipper gave Rockne before he died, there was a problem.

Notre Dame knew it was a hoax Dec. 26. But the school didn’t call a news conference or issue a statement revealing that the girlfriend story was pure baloney. So Notre Dame is complicit in the lie. And all the spinning Wednesday night by ND athletic director Jack Swarbrick can’t change it.

He called it “a sophisticated hoax” and said Notre Dame didn’t come forward because “this was Manti’s story to tell.”

Really?

Swarbrick is the same mealy-mouthed bureaucrat who defended the football program after student videographer Declan Sullivan, a 20-year-old native of Long Grove, Ill., was sent into that scissor lift in the high wind and died when it collapsed in October 2010.

Swarbrick said then that the weather conditions before the tragedy were “unremarkable,” even though Sullivan told friends on social media that there were “gusts of wind up to 60 mph” and he was afraid he would die.

Notre Dame’s company line isn’t any more convincing now than it was then.

The school fell in love with the Te’o girlfriend myth, which ripened in September after the Michigan game. A Chicago Tribune story recounted Te’o’s comments about what “Lennay” told him before she died.

“She said, ‘Babe, if anything happens to me, promise that you’ll still stay over there and that you’ll play and that you’ll honor me through the way you play,’ ” Te’o said. “All she wanted was some white roses. That’s all she asked for. So I sent her roses, and sent her two picks along with that.”

White roses, and two interceptions. Babe, how cool is that?

It almost makes you want to scan the Midwestern horizon during a thunderstorm, to see the lightning flash and strike the great oak tree on the family farm.

And the young Roy Hobbs, who’d grow up to be the greatest baseball player who ever lived and looked exactly like Robert Redford, would take a chunk of that magic wood and carve the amazing bat known as Wonderboy. He’d burn a crude lightning bolt into the wood, a symbol of its Arthurian power.