'It Was Devastating': Prince William Left Heartbroken After Discovering Kate Middleton Was Diagnosed With Cancer

Kate Middleton was diagnosed with cancer earlier this year, and it took a toll on her husband, Prince William , a new biography claims.

“It was devastating for him,” royal author Robert Jobson told an outlet while promoting Catherine, the Princess of Wales.

According to Jobson, William had “a lump in [his] throat” or “the empty feeling in his stomach” when he learned about Kate's condition .

“It wobbled him,” the author continued. “There’s no doubt about that.”

The future queen took six months away from the spotlight to focus on her health, but she returned to public duties at Trooping the Colour in June .

"I have been blown away by all the kind messages of support and encouragement over the last couple of months. It really has made the world of difference to William and me and has helped us both through some of the harder times. I am making good progress, but as anyone going through chemotherapy will know, there are good days and bad days. On those bad days you feel weak, tired and you have to give in to your body resting. But on the good days, when you feel stronger, you want to make the most of feeling well. My treatment is ongoing and will be for a few more months," the princess wrote via Instagram on Friday, June 14.

The mom-of-three was honest about the impact chemotherapy has on her.

"On the days I feel well enough, it is a joy to engage with school life, spend personal time on the things that give me energy and positivity, as well as starting to do a little work from home," she continued.

OK! previously reported a source applauded William for caring for Kate and their three kids, Prince George , Princess Charlotte and Prince Louis .

“He’s shouldered a lot of the responsibilities, and, what’s more, he seems to be having fun doing it. Kate has seen the change, and she’s genuinely touched by all that he’s doing, not just for her, but for the children ," a source shared.

William and Kate's romance has only strengthened since they met at St Andrews.

“They remember their vows they said at their wedding ,” an insider said of the special moment. “It forced her and William to take a good look at their priorities and be more grateful for what they have. Their vows have never been more profound as they navigate this difficult time.”

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Though William, was "already hands-on," "he’s become more confident and stronger in his role as dad. It’s reassuring for Kate to know the kids will always have a loving, compassionate and caring relationship with their father if, God forbid, something happens to her," the insider dished.

Jobson spoke to Us Weekly .