Q. I just split up with my ex-wife. She told me our last child was not mine and I just couldn't take it anymore. I demanded a DNA test – and sure enough she was right. But, then I got the bright idea to test my daughter who is three years older than the baby, and sure enough, she's not mine, either. This is the worst thing that has ever happened, and I am at a loss. I'm not sure I want to leave forever. What about my kids? Do I have to tell my daughter she's not mine? What's good ex-etiquette?