Stephen Colbert adds to apologies after Kate Middleton's cancer announcement

Late-night host Stephen Colbert sent well wishes to Kate, the Princess of Wales, on his show Monday night, two weeks after going viral with a "spilling the tea" monologue about the rumors surrounding the royal.

In the wake of that monologue, Colbert was criticized for giving light to the frenzy of online rumors about Kate amid her absence from public duties after undergoing abdominal surgery in January.

The criticisms he and others faced grew after the 42-year-old mother-of-three announced Friday she had been diagnosed with cancer.

"We do a lot of shows, and I tell a lot of jokes, and I tell jokes about a lot of different things -- mostly what everybody's talking about," Colbert said Monday night. "And for the last six weeks to two months, everybody has been talking about the mystery of Kate Middleton's disappearance from public life."

He continued, "And two weeks ago, we did some jokes about that mystery and all the attendant fru-fra in the reporting about that, and when I made those jokes, that upset some people, even before her diagnosis was revealed, and I can understand that."

Colbert went onto send Kate "well wishes," noting that he holds himself to a standard in which he "does not make light of someone else's tragedy."

"I don't know whether her prognosis is a tragic one ... but regardless of what it is, I know, and I'm sure many of you, far too many of us know that any cancer diagnosis of any kind is harrowing for the patient and for their family," Colbert said. "And though I'm sure they don't need it from me, I and everyone here at 'The Late Show' would like to extend our well wishes and heartfelt note that her recovery is swift and thorough."

Colbert's decision to address his jokes about Kate came just days after actress Blake Lively was among the first to publicly apologize in the wake of Kate's disclosure of her cancer diagnosis, which the princess delivered in an emotional video message.

Lively, a mom of four, spoke out after posting a photo on Instagram that seemed to play off the controversy around Kate's Mother's Day photo, which showed the royal with her three kids.

The photo Kate shared on social media on March 10 was later retracted by multiple news agencies over concerns it was "manipulated." The pic -- for which Kate issued a public apology for "any confusion" it caused -- was the first official photo released of the princess since she underwent abdominal surgery in January and took time off from her public duties.

Lively's since-deleted post, shared to promote her drink company, showed the actress holding a beverage in a visibly edited photo, with exaggerations like a giant thumb and a giant lemon falling from the sky.

"I'm sure no one cares today but I feel like I have to acknowledge this," Lively wrote in an Instagram story Friday, without naming Kate. "I made a silly post around the 'photoshop fails' frenzy, and oh man, that post has me mortified today. I'm sorry. Sending love and well wishes to all, always.❤️."

Kate's absence from the public eye combined with the photo controversy, a lack of updates from Kensington Palace about her health and Kate's husband, Prince William, missing a royal engagement due to a "personal matter" led to a frenzy of rumors online about Kate's health and well-being.

In a video message shared by the palace on Friday, Kate put those rumors to rest with an emotional announcement that shocked the general public and close royal watchers alike.

"The surgery was successful," Kate said of her abdominal surgery in January. "However, tests after the operation found cancer had been present. My medical team therefore advised that I should undergo a course of preventative chemotherapy and I am now in the early stages of that treatment."

While Kate did not disclose what type of cancer had been found or any further details about her treatment, the 42-year-old delivered the news of her cancer diagnosis and treatment on her own and in her own words. Kate wrote the remarks herself, ABC News confirmed.

The weight of the very personal news Kate shared seemed to spark remorse in people who traded rumors about her health online.

"Yeah i definitely feel bad about laughing at all the 'KateGate' memes. wishing her a speedy recovery," Saint Hoax, an influencer with 3.4 million followers on Instagram, wrote Friday in a post sharing the video of Kate.

Lauren and Chanler, two sisters behind "Pop Apologists," a podcast and Instagram account with over 280,000 followers, also issued an apology while announcing they had taken down a multi-part series about Kate that featured some of the most widely-spread videos during the height of the "where's Kate" frenzy.

"Throughout this whole process, we knew there were a lot of possible outcomes. This feels like one of the worst," the sisters wrote on Instagram. "We are truly devastated by this development but hopeful to hear that the chemotherapy is preventative. Our admiration of Princess Catherine has never wavered and we are just now praying for her to continue getting healthier every day."

In one of two podcast episodes devoted to the topic of Kate prior to her cancer announcement, the sisters described the Kate rumors as becoming "darker and more sinister," and placed blamed for the turn of events on the silence of Kensington Palace, the office of William and Kate.

"It feels like we are no closer to the truth and every day that goes by that we are no closer to the truth, it seems like, wow, there must be something big that is happening, otherwise they could just literally put a lid on this so easily with a quick, quick high-res Zoom," the sisters said in a March 19 podcast episode. "It's that simple."

Others shared similar sentiments in the wake of Kate's announcement, arguing that had the palace been more forthright earlier on, the story may have gone away more easily.

Prior to Kate's video, the last update on the princess shared by the palace came in late February, when the palace said she was "doing well" as she continued to recover.

The spokesperson also brushed off online speculation at the time, telling ABC News in a statement, "Kensington Palace made it clear in January the timelines of the Princess' recovery and we'd only be providing significant updates. That guidance stands."

Kate said in her message that she and William tried to "process and manage" the news of her cancer diagnosis privately.

"As you can imagine, this has taken time. It has taken me time to recover from major surgery in order to start my treatment," Kate said. "But, most importantly, it has taken us time to explain everything to George, Charlotte and Louis in a way that is appropriate for them, and to reassure them that I am going to be OK."

ABC News royal contributor Victoria Murphy noted that Friday, the day of Kate's announcement, was also the last day of school for George, 10, Charlotte, 8, and Louis, 5, before their Easter holiday break.

"They've been considering how to talk to their children about it, bearing in mind that their children go to school, they go to school with other children, they interact with the children," Murphy said of William and Kate, adding, "I think the timing of this announcement is about the fact that they can now take the children away from the outside world."

Just as they did when Kate underwent surgery in January, palace officials said Friday they would not be providing constant updates on Kate's health in the days and weeks ahead, telling reporters, "We will not be sharing any further private medical information. The Princess has a right to medical privacy, as we all do."

In regards to when Kate may return to her public duties, the palace said only, "Kensington Palace will provide information, when the time is right, and The Princess is able to restart work and her duties. In the meantime, we would ask that the family's privacy is respected."