Kate Middleton’s brother is speaking out after his oldest sister revealed publicly that she is battling cancer.

James Middleton’s Instagram post comes after Kate shared a heartbreaking video explaining what she and her family have been enduring ever since she underwent serious abdominal surgery back in January.

The post from James Middleton revealed a never-before-seen photo of himself and Kate as children. “Over the years, we have climbed many mountains together. As a family, we will climb this one with you too,” James wrote.

Beautiful.

In the video shared with the world on March 22, Middleton announced that she was diagnosed with cancer following the major abdominal surgery she underwent at the beginning of the year. The princess called the diagnosis “a huge shock” to herself and her family.

“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.”

After thanking people all over the world for their encouraging words and “wonderful messages of support,” Middleton continued to say her and Prince William’s focus has been their three children.