My husband used to mock my age and how I looked at 50. At first, it seemed like harmless jokes, but then I realized he actually meant them. Soon, it became public. His friends all had younger wives, and even they joked about me at parties—he just laughed along. But the worst part? At my 50th birthday party, in front of everyone, he confessed he had a 25-year-old mistress—and she was at the party!!! My world split in two right then. But karma didn’t wait. Still at the party, in front of everyone, my husband…