NEW YORK Grammy-winning country singer Kacey Musgraves and her musician-husband, Ruston Kelly, have filed for divorce. In a joint statement, Musgraves and Kelly said weve made this painful decision together." It won her the best country album Grammy and one of its singles, Merry Go Round, won best country song. Kelly has also written songs for other artists, including Tim McGraw, Hayes Carll, Lucie Silvas and Josh Abbott Band. Musgraves co-wrote Miranda Lamberts 2013 country hit, Mamas Broken Heart, earning herself a Grammy nomination as a songwriter.