King Charles, Who Has Cancer, 'So Proud' of 'Beloved Daughter-in-Law' Kate Middleton amid Her Cancer Diagnosis

The Princess of Wales announced on Friday that she is undergoing treatment for cancer

King Charles is supporting his daughter-in-law Kate Middleton amid her cancer diagnosis.

On Friday, the Princess of Wales, 42, shared a personal video message that she is undergoing treatment after post-operative tests following her abdominal surgery in January "found cancer had been present."

Charles, 75, who is also undergoing cancer treatment, is "so proud of Catherine for her courage in speaking as she did," a Buckingham Palace spokesperson tells PEOPLE.

King Charles and Princess Kate were both hospitalized at The London Clinic in January, and the monarch has "remained in the closest contact with his beloved daughter-in-law throughout the past weeks," the spokesperson adds. Both King Charles and Queen Camilla "will continue to offer their love and support to the whole family through this difficult time."

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Related: Kate Middleton Reveals She Has Cancer and Is Getting Chemo, Says It Has 'Taken Time' to Tell Her Kids

In her emotional video, the Princess of Wales began by thanking well-wishers for their "wonderful messages of support" amid her recovery during what has been "an incredibly tough couple of months for our entire family."

"In January, I underwent major abdominal surgery in London, and at the time, it was thought that my condition was non-cancerous," she shared. "The surgery was successful. 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."

Noting that the news was a "huge shock," Princess Kate said that she and Prince William "have been doing everything we can to process and manage this privately for the sake of our young family. As you can imagine, this has taken time. It has taken me time to recover from major surgery in order to start my treatment."

"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," she said, referring to her three children: Prince George, 10, Princess Charlotte, 8, and Prince Louis, 5.

"As I have said to them; I am well and getting stronger every day by focusing on the things that will help me heal; in my mind, body and spirits."

Kate continued, "Having William by my side is a great source of comfort and reassurance too. As is the love, support and kindness that has been shown by so many of you. It means so much to us both. We hope that you will understand that, as a family, we now need some time, space and privacy while I complete my treatment. My work has always brought me a deep sense of joy, and I look forward to being back when I am able — but for now, I must focus on making a full recovery."

"At this time, I am also thinking of all those whose lives have been affected by cancer. For everyone facing this disease, in whatever form, please do not lose faith or hope," she concluded the video. "You are not alone."

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