'Heartbroken': Kate Middleton and Prince William Are 'Going Through Hell,' Their Pal Claims

The prince and princess of Wales have been keeping a low profile since the announcement of Kate's cancer diagnosis.MEGA

One of Kate Middleton and Prince William's pals and the go-to designer behind many of the looks worn by their children Prince George, Prince Charlotte, and Prince Louis is worried about the royal couple as the Princess of Wales undergoes cancer treatment, RadarOnline.com has learned.

"I'm heartbroken at the moment. I think they are going through hell," Amaia Arrieta told The Telegraph. "I hope they will be back. It's really personal."

Kate is focused on her recovery.MEGA

"Dressing the royals gives me so much pride, I really do care about how they look," she said. "The first time I realized Prince George was wearing my designs, I was in Waitrose and saw the picture of him on the cover of Hello! magazine. That was a huge moment because they had been coming to us, but you never know if they’ll actually wear it."

Arrieta has been dressing Prince George since he was a baby and works closely with the Wales' team on outfits for special occasions including birthdays, weddings, and Christmas Day church services. "It's often a very tight deadline," she added. "We would do anything for them...the children always look amazing in the end."

Arrieta was thrilled when she saw the Mother's Day family photo posted by Middleton earlier this year and noticed that Princess Charlotte, who celebrated her 9th birthday on May 2, was wearing a checked skirt from her childrenswear label, Amaia London.

But that same photograph proved a source of controversy after it was pulled by several major news agencies due to suspicions that it was "manipulated" by Kensington Palace, leading to further speculation about Middleton's health and whereabouts.

"Like many amateur photographers, I do occasionally experiment with editing," Middleton wrote in a statement soon afterwards. "I wanted to express my apologies for any confusion the family photograph we shared yesterday caused."

Kate Middleton and Prince William have thanked the public for their support following the Princess of Wales' cancer diagnosis.MEGA

Less than two weeks later, amid mounting conspiracy theories, Middleton revealed in a heartfelt video that she had been diagnosed with cancer and was in the early stages of chemotherapy treatment following her abdominal surgery in January.

"It has been an incredibly tough couple of months for our entire family, but I've had a fantastic medical team who have taken great care of me, for which I am so grateful," she said.

"We hope that you'll understand that as a family we now need some time, space, and privacy while I complete my treatment," she added. "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."

"We hope that you'll understand that as a family we now need some time, space, and privacy while I complete my treatment," Middleton said.MEGA

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Kate's diagnosis followed King Charles III's own cancer diagnosis, which was revealed in February shortly after her abdominal surgery.

In a statement shared via Buckingham Palace, Charles said he is "so proud of Catherine for her courage" and that he has "remained in the closest contact with his beloved daughter-in-law throughout the past weeks."