Hello "I seriously screwed up!
" Unless it was something very important I would have just left it in and sewed a fancy stitch over it so it could not reallly show. I did that once where I sewed ever other piece of fabric wrong side up. I just covered it up with a patch of the same material I mess up on. I used a star from my cookie cutters. Any more for me it just takes too much time to "unsew" something that big. I would have just went for it and let the threads fall where they may! Just me....