In a video statement read from an autocue, you could almost see the shadow of shock still lingering about his jowls.
The thunderous insight that had just befallen him? That, apparently, women are not objects that exist purely for men's sexual gratification.
If that weren't enough of a shock for the presidential wannabe, two more frightening revelations slipped past the doorman at Trump Tower, and made their way up the elevator: that men who love and respect women dislike men who make misogynistic comments about women.
And the kicker: women, and the men who love them, vote.
When you're faced with a political candidate with the subtlety and sensitivity of a machine gun, it is poetic that the thing to inflict grievous damage to his campaign is about as basic as it comes.
In any normal election, you would expect that at least the appearance of respect for women would be a prerequisite for those seeking office.
While Megyn Kelly, Rosie O'Donnell and Hillary Clinton, among many others, have dutifully tried to warn him, it wasn't until the Washington Post lobbed a bomb that Trump finally got the memo.
The hot-mic video from an Access Hollywood segment 11 years ago may well go down in history as one of the most destructive leaks of the modern political era.
If we're to believe the murmurings on social media of various former producers on Trump's show The Apprentice there's more - and worse - where that came from.
As this election has morphed from political theatre to theatre of the absurd, the landscape has shifted.
The emergence of identity politics is due to a political system that affords certain groups a voice, and silences others.
Women have suddenly become the most powerful group in the electorate. What Trump sought to dismiss as "locker room banter" was condemned not only by outraged feminists but also by disgusted conservative men.
It may have taken until 2016, but the idea that treating women like living sex toys is abhorrent has finally gone mainstream.
In this great year of slow-dawning realisations, American politicians have also been forced to wake up to the fact that women are voters with minds of their own, who don't respond well to a veritable slew of misogynistic comments from a man who is asking them to vote for him.
Call it identity politics if you like, but alienating half the population is a huge problem, whichever way you look at it.
For those of us who abhor xenophobia, racism, misogyny and other such repugnance, seeing Trump take his place behind a microphone now has an almost Pavlovian effect.
We begin to froth at the mouth before he's managed to so much as pucker his fleshy maw. The only shocking thing about Trump's comments to Billy Bush is that the people now fleeing the Trump camp in droves were quite happy to stand alongside him as he attacked Mexicans, Muslims and people of colour.
What Trump's supporters are finally learning is that identity matters.
The right, particularly, have tried to smear identity politics, insinuating that a belief motivated by the experiences of one's identity group is somehow invalid or unworthy. In a nutshell, what one feels, "as a woman", "as a Muslim" or, "as a Mexican" is irrelevant.
What's hiding beneath the surface is the knowledge that if the lived experiences of the marginalised were to carry any political weight, the traditional power structures would be blown to smithereens.
If women, Muslims, Mexicans, African-Americans, the LGBTQ+ community and other marginalised groups came together and organised, they would form a formidable bloc - a frightening prospect to the white male-dominant status quo.
The emergence of identity politics is due to a political system that affords certain groups a voice, and silences others.
It is an indication that modern democracy is deeply flawed and that it will take immense consciousness-raising to fix it.
America has been given a harsh jolt from ignorance to awareness this week. After Trump's disastrous tape leaked online, Canadian author Kelly Oxford asked women to share their experiences of sexual assault on Twitter.
More than a million women replied to her to share their stories. The experiences of the many millions of women globally (of which I am one) who have had an intimate part of their anatomy groped by a man without their consent have spoken loud and clear, and men have finally listened.
That unfortunately hasn't stopped a group of them from using alleged victims of sexual violence for their own gain.
Make no mistake, Trump - a man who bragged about, then minimised, sexually violating women against their will - holding a press conference with alleged victims of Bill Clinton is no victory for survivors of sexual assault, but an example of further exploitation.
Attempting to blame Hillary for her husband's conduct is yet another example of just how alarmingly little respect Trump has for women.
The only thing that remains to be seen is just how low he can go.
