Article continues below advertisementPrince William felt tremendous pressure to persevere amid his wife Kate Middleton's cancer battle.The upcoming book William and Catherine: The Monarchy's New Era: The Inside Story reveals the 43-year-old assumed primary responsibility over their children while the Princess of Wales was in the hospital.Article continues below advertisementSource: MEGAKate Middleton underwent chemotherapy.To take some of the weight off the 44-year-old, William tended to the kids and took them to school every day.