Kate Middleton has resurfaced on social media, breaking her silence for the first time since undergoing successful abdominal surgery in January, RadarOnline.com has learned. The Princess of Wales, 42, took to Instagram and X (formerly Twitter) to share a sweet family photo of herself sitting in a chair surrounded by her children Prince George, 10, Princess Charlotte, 8, and Prince Louis, 5, taken by her husband Prince William, 41, in honor of Mothering Sunday in the United Kingdom. “Thank you for your kind wishes and continued support over the last two months. Wishing everyone a Happy Mother’s…