I always thought we were a happy little family. My partner Mike and I had been together five years, we owned a home, and we were raising our sweet four-year-old son, Luke. Life felt solid—until the day Luke told me he had a “secret sister.” It came out so casually on the way home from daycare: “She was at our house. Daddy said not to tell.” I froze. I asked her name. “Mia,” he said. “She has pretty braids.” That night, I confronted Mike. Instead of answering, he proposed. He knelt down with a ring and tried to distract me like he always did when things got uncomfortable. But this time, I didn’t fall for it. He claimed Mia was just the daughter of a coworker who stopped by briefly. But something didn’t sit right. So the next day,