Kelly’s husband Michael raised thousands of pounds by running from Ewloe to Bristol, hoping to pay for her to have the surgery in the USA.
She had the operation in the UK in June.
But her health – which the couple have documented on social media – continued to deteriorate.
In a post on Facebook, Michael Pendry said his “amazing and beautiful wife” died early on Sunday.
She “fought until the very end, her spirit and strength was incredible as always,” he added.