By Brandy McDonnellWatch Oklahoma country music star Blake Shelton perform an emotional, stripped-down acoustic version of his ballad "Over You" in memory of his friend Troy Gentry Wednesday night at the Grand Ole Opry in Nashville, Tennessee.Shelton co-hosted with Storme Warren the Troy Gentry Foundation concert in honor of the Montgomery Gentry singer, who died in a 2017 helicopter crash, and surprised the audience with his stirring performance.