Here’s what I’m wondering: Was it Alicia Machado’s really mild sex video that caused Donald Trump to wake up with a start about 3:00 the other morning? What was he thinking about as he fired off that “unhinged” tweet about her recorded activities under the sheets? And, yes, conscientious journalist that I am, I forced myself to see the tape of her romp. Talk about boring — unless you are amused by how unexciting it really was. But apparently Donny found it far more interesting. Something got him going, whatever he was thinking, or maybe fantasizing, as he grabbed his device and pecked out: “Did Crooked Hillary help disgusting (check out sex tape and past) Alicia M become a U.S. citizen so she could use her in the debate?”

Actually, he didn’t send that one till 5:30 a.m. He obviously was still seething about how Hillary Clinton had blindsided him in their first debate over his cruel handling of his Miss Universe, who was the very same Alicia Machado, when she won the beauty contest 20 years ago. Hillary had him backpedaling as she attacked him for being a serial misogynist. That’s when she brought up Ms. Machado and her descriptions of how Trump, who ran the competition, made her life a living hell when she gained some weight. According to Alicia, he ridiculed her as “Miss Piggy.” Trump didn’t deny it. Adding to his cruelty, he resorted to an ethnic slur to describe Miss Venezuela/Universe as “The Housekeeper.”

As much as anything else, Hillary Clinton won the debate when she drew blood by confronting him with Machado’s charges. By the way, Hillary did win the debate, even though Trump’s various toadies tried to cite totally unscientific web surveys that named him as the victor. Even so, it could have been forgotten after a day or so, except that Donald Trump, like the elephant he is, never forgets. He couldn’t let it go, as we found out several days later when he fired off his early-morning tweets. And by the way, if he called Machado “Miss Piggy,” can the overweight Trump be called “Mr. Elephant”? Sure. What’s good for the piggy is good for the elephant. Or something like that.

The truth is that fat-shaming is as cruel as any other prejudice. It’s particularly unfair to women, who still are victimized by a double standard about their looks. An argument can be made that pageants like Miss Universe perpetuate a dangerously unrealistic expectation that’s harmful to women. Of course, that would appeal to a warped sleaze like Donald Trump, a dirty old man if there ever was one.

As we’ve discovered, though, his cruelty is not limited to fat-shaming or misogyny. He is an equal-opportunity bigot. He has managed during this single campaign to insult Hispanics, blacks, Muslims, the disabled — just about everyone but poorly educated white guys. In spite of that, he has attracted millions of passionate supporters. Actually, it’s more accurate to say that it is because of that, which makes his followers pretty, what’s that word, “deplorable.”

Because he’s lately paid attention to his advisers, he’s managed to soften his most egregious verbal assaults, mostly sticking to the script and even discussing substance, albeit pretty superficially. This seemed to camouflage his narcissistic nastiness. By doing so, he had moved into a tie with Hillary. Of course, she and her people have helped with an inept campaign.

Trump is now threatening to bring up all the ugly memories of Bill Clinton’s infidelities. Considering his unsavory marital record and those of his two loudest surrogates, Rudy Giuliani and Newt Gingrich, that could severely backfire. Hillary has already called his tweet “unhinged.” Ultimately, this election could hinge on his being unhinged, and his inability to hide it. The country’s well-being also hinges on it.

Bob Franken is a longtime broadcast journalist, including 20 years at CNN.