American Idol winner and pop star Kelly Clarkson married music manager Brandon Blackstock over the weekend.Clarkson, 31, took to her social media to announce the nuptials, writing on her Twitter account, "I'm officially Mrs. Blackstock."The pair married at Blackberry Farms, near the Great Smokey Mountains, in Walland, Tennessee Sunday. Clarkson and Blackstock, the stepson of country singer Reba McEntire, have been dating for two years. The couple announced their engagement last year.