SEATTLE — An Olympic swimmer who accused her former coach of sexually abusing her as a minor described “an extensive, abusive and incredibly manipulative relationship” that spanned a decade in an emotional essay Friday. Ariana Kukors wrote online that Sean Hutchison meticulously controlled and manipulated her from a young age and that the abuse at times overshadowed the successes she experienced swimming, including at the 2012 Olympic games in London, where she placed fifth in the 200-meter individual medley. “I think back on those times now, tearfully asking why no one helped me … why no one stepped in to save me from this monster. It’s still hard to comprehend, but Sean had perfected the art of grooming; I wasn’t even aware I needed