Let’s talk about what Fiona Hill said.

The former White House Russia adviser testified last week in the House impeachment investigation, one of a number of nonpartisan civil servants who came forward to shed light on Donald Trump’s attempt to strong-arm Ukrainian President Volodymyr Zelensky into investigating a political rival. Their cool professionalism offered a useful contrast with the heated histrionics of Republicans on the panel, their facts and specifics colliding like bumper cars with the fact-free accusations and vague conspiracies of the Trump defenders.

Hill, in particular, was quietly devastating.

In her opening statement, she rebuked conservatives’ fascination with bizarre and Byzantine theories for which they have no evidence. Like their stubborn insistence that Ukraine interfered with the 2016 election: The U.S. intelligence community has said quite clearly that it was Russia that meddled in American affairs, a conclusion Trump — and thus, his enablers — famously decline to accept.

“Some of you on this committee,” said Hill, in the crisp and precise accent of her native England, “appear to believe that Russia and its security services did not conduct a campaign against our country — and that perhaps, somehow, for some reason, Ukraine did. This is a fictional narrative that has been perpetrated and propagated by the Russian security services themselves.”

This inability to agree on reality, she said, is producing dire consequences. “Our nation is being torn apart.”

All of which raises pointed questions: Given that they not only intervened to help Trump but also, as “60 Minutes” reminded us on Sunday, to undermine Democratic congressional candidates, why do the Russians have such a clear preference for Republicans? Why haven’t Republicans been challenged to explain that? And why don’t more of us seem to care? Why is this not a hair-on-fire, shouting-in-the-streets national emergency?

Some of us are old enough to remember the time, not so long ago, when Russia was the bete noire of conservatism, when Ronald Reagan, the archangel of the right, declared the old Soviet Union “the evil empire.” So there is for us a sense of jaw-dropping, head-snapping cognitive disconnect at hearing Republicans, of all people, minimize a Russian attack upon the United States. It’s as if the Ku Klux Klan ran a membership drive for the NAACP — and black people just shrugged.

That’s how broken this nation is, the degree to which Fox, Facebook, Alex Jones, Breitbart, anti-vaxxers and other misinformation peddlers have damaged not simply our ability to discern the truth, but even our ability to care. Kellyanne Conway blithely demands that we respect “alternative facts.”

But the alternative to fact is chaos. For Exhibit A, turn on your television — or just open your front door.

Trump did not create this problem — in fact, it created him — but he has certainly weaponized and exacerbated it with reckless abandon. He has taken what was already awful and made it exponentially worse, as the lapdogs of his party follow in lockstep, happy to break the broken nation, so long as they get anti-abortion judges and tax cuts. Apparently, that’s the going price of a human soul.

So we would be well advised to take seriously Hill’s warning.

One is reminded of another presidential counselor who spoke truth to power. But John Dean’s words to Richard Nixon don’t begin to touch the magnitude of our present crisis. In 1974, yes, there was “a cancer on the presidency.”

But in 2019, the cancer is the presidency.

— Leonard Pitts is a Pulitzer Prize-winning columnist for The Miami Herald.