MAUREEN CALLAHAN: The sad truth is that even Kate's cancer won't spark a Sussex reconciliation. After all the endless leaking, petty parasitic mudslinging and sick slurs, how COULD they be trusted?

Will Kate Middleton's cancer diagnosis finally smack some sense, some decorum and humility, into House Sussex?

Don't bet on it.

On Friday, hours after the Princess of Wales released her video message to the world, Harry and Meghan issued a statement from Montecito.

Loving and expansive it was not.

'We wish health and healing for Kate and the family' — not William by name, nor young George, Charlotte, and Louis — 'and hope they are able to do so privately and in peace'.

Compared to King Charles's effusive pride for his 'beloved daughter-in-law' and her 'courage' in going public, this feels… lacking.

Where was the sense of familial love – or anything remotely personal about the woman Harry once called 'the big sister I never had'?

Will Kate Middleton's cancer diagnosis finally smack some sense, some decorum and humility, into House Sussex? Don't bet on it.

On Friday, hours after the Princess of Wales released her video message to the world, Harry and Meghan issued a statement from Montecito. Loving and expansive it was not. Where was the sense of familial love - or anything remotely personal about the woman Harry once called 'the big sister I never had'?

Just one emotionally stingy, generically boilerplate line. From two people never short of words to describe their complaints.

Doubtless there was grievance behind this statement.

After all, the Duke and Duchess reportedly learned the terrible news about Kate along with the rest of us.

'They had no idea,' a source told the New York Post.

Of course not! It seems the only people surprised by that are the Sussexes themselves.

Following their bloodless statement came another colossal misstep, the news that Harry and Meghan had privately reached out to Kate on Friday night.

Is it really a private gesture if the world's media has subsequently been notified?

These two just cannot get out of their own way. If they had any hope of rebuilding an iota of trust with Kate and William, none of us would ever have known of these 'private' messages.

Harry and Meghan, despite cawing relentlessly about the intrusive media — of which they are a part, what with Netflix and podcasts and book deals and a pending cooking show and countless interviews and speeches — have zero concept of discretion.

They remain incapable, despite this gravest of moments, to realize when a story has nothing to do with them.

Or when it might serve everyone, their ailing sister-in-law and her small children especially, for them to keep their mouths shut.

Not such a big ask, is it?

As ever, it seems that this was all meant to redound to Harry and Meghan's benefit.

We are to understand that despite their most serious estrangement, they are both still in regular contact with the future King and Queen.

Please. As if Kate and William don't screen their calls and messages.

According to reports in the Telegraph this weekend, the Waleses have now put the so-called 'Harry problem' well behind them — note that dismissive description, as if Harry is a gnat, Meghan not even mentioned — especially as King Charles, too, is battling cancer.

What else, really, could the Sussexes expect?

Following their bloodless statement came another colossal misstep, the news that Harry and Meghan had privately reached out to Kate on Friday night. Is it really a private gesture if the world's media has subsequently been notified?

Harry and Meghan, despite cawing relentlessly about the intrusive media - of which they are a part, what with Netflix and podcasts and book deals and a pending cooking show and countless interviews and speeches - have zero concept of discretion. They remain incapable, despite this gravest of moments, to realize when a story has nothing to do with them .

Just one week before Kate's announcement, while speculation surrounding her health was at fever pitch, Meghan took that opportunity to announce the launch of her home goods line. On Instagram.

If that doesn't display a sense of proportion, good taste and the domestic family warmth Meghan is peddling — well, what does?

But Meghan just had to get out there, even though her eight-millionth relaunch, this one bearing the deliciously tacky brand name 'American Riviera Orchard', has no products for sale. As yet, anyway.

The world breathlessly awaits Meghan's jams and jellies.

This pettiness was compounded, hours later, by H&M's announcement of a $100,000 'NAACP-Archewell Foundation Digital Civil Rights Award', all on the same day as the 25th annual Diana Awards in London — where Prince William appeared in person, Harry via video call after William had left.

Harry and Meghan have proved themselves utterly parasitic.

And the cruelty of Harry, having implied publicly that his brother hadn't married for love; reprinting text messages from Kate to Meghan in 'Spare'; sitting idly by while Meghan reminded the world of the 'Waity Katie' nickname on Oprah; not saying a word when Kate and Charles were named as the so-called 'royal racists'.

Did he or Meghan think, for a moment, of the stress this may have caused Kate?

Recall that when Harry attended Prince Philip's funeral alone, Meghan made it known that she and Harry personally selected locally sourced flowers (of course) representing Philip's Greek heritage, along with a handwritten note.

With that gesture, Meghan, her mouthpiece Omid Scobie said, 'did her bit'.

Reptilian, that coldness.

It was also at Philip's funeral, remember, that Kate quietly stepped back to allow William and Harry to walk together, encouraging some form of rapprochement.

That's class. Kate tried. She showed her substance in that moment, a quality that will forever elude Meghan.

What must our Duchess think of the global goodwill Kate's received?

American television interrupting live sports for Friday's announcement, the White House sending thoughts and prayers, Kate on the front page of every major newspaper across the globe.

All Meghan has is social media and Omid Scobie.

Speaking of Scobie: It was he who tweeted, quite disgustingly, a 'countdown clock' to the exact moment when Kate's health update was due to be broadcast.

After considerable backlash, Scobie said he meant no harm.

In fact, he said it was the media who were 'sick and disgusting' for finding his post 'tasteless'.

Projection, thy name is Scooby-Dooby-Doo.

All Meghan has is social media and Omid Scobie. Speaking of Scobie: It was he who tweeted, quite disgustingly, a countdown clock to the exact moment when Kate's health update was due to be broadcast.

But that's the hall of mirrors in House Sussex, isn't it? Someone else is always the problem, always to blame, Harry, Meghan and their supporters ever the victims.

And what of their friend Christopher Bouzy?

He's been out front since Kate's announcement claiming that the royal family not only 'lied' but fed into all the conspiracy theories going around, appearing to compare the princess's video to 'North Korean propaganda'.

If Harry and Meghan had any intention of showing good faith to the royals, they would tell Scobie and Bouzy to shut up.

But they won't. They can't. The Sussexes are constitutionally incapable of behaving like adults who have their priorities in order, their values in check, and who have nothing but regret for causing pain to Kate, the last person who deserved it.

If there was ever the slightest hope for a reconciliation, that's over for good.

Stress is the last thing anyone fighting cancer needs. How necessary, then, for Harry and Meghan to be well and truly shut out.