Oh, I feel your devistation! But look at the bright side!
You have a chance to add to the story of the quilt for a future chapter!
I would flatten out the quilt and make it as clost to what it was. Then find a piece of material that would look right with the rest of the quilt. Then draw out something large enough to cover the area and using something like steam-a-seam lite (for applique)apply the patch over the area, and then do the same on the back. Use a matching thread to stitch the patch down. You could use a wheel pattern or a heart with a broken zig zag down the center of it. Look at the mishap as a way to add to your experience. This is how I have learned over my many years of sewing!! Good luck and don't forget to show us the outcome. A big hug for sympathy and encouragement!