Kate, Britain’s Princess of Wales, thanked the public on Sunday for their support in her first public message since undergoing abdominal surgery in January, posting a picture of herself with her three children.The photograph, taken by her husband, heir to the throne Prince William, showed Kate, 42, smiling and looking healthy surrounded by Princes George and Louis and Princess Charlotte.“Thank you for your kind wishes and continued support over the last two months,” Kate wrote in a message on X. “Wishing everyone a Happy Mother’s Day.”Mother’s Day is celebrated on Sunday in…