It was two in the morning when my phone buzzed with a WhatsApp group invite from an unknown number. "Mistress #1, #2, #3—guess which one you are?" I thought it was some childish prank and was about to leave, but then a video appeared in the chat. My husband was celebrating a birthday with another woman, and the child in her arms called him "Daddy". “I immediately called him, but a woman's mocking voice answered. "Oh look, the 'old hag' Mr. Carter saved in his contacts is calling. Who even are you?" …