I'd probably make another section just like the portion that is turned around and carefully applique it down (with a turned under edge), then turn the quilt over and use the quilting on the back of the quilt as a guide to re-quilt that section. If you stitch the appliqued section very close to the edge, and then quilt it, it will be barely noticeable. Good luck with your decision and the outcome. I know it's so disappointing when this happens