Could letting your man sleep with another woman help your relationship? Author and former mistress Holly Hill thinks so. "One of the main things that I have learned is that a woman that negotiates infidelity with her partner is far more powerful than a woman who is sitting home wondering why he's late from the office Christmas party," she says. "It's better to walk the dog on a leash than let it escape through an unseen hole in the back fence." Hill's memoir, "Sugarbabe" details her yearlong adventure with a series of so-called "sugar daddies." The book sold 24,000 copies...