Ouch! Hate it when things like that happen.
My usual solution is when I can't hide it, I make a little heart shaped applique or embroidery lazy daisy or something that acknowledges and fixes, even if it doesn't hide. You could cut out and inset in a new piece. You could carefully seal the area with an iron on patch, I'd probably do that as a pretty big circle and then stitch it down with thread that matches the background.
During the summer I found a flaw in my backing fabric after I had completely quilted and washed it... grrr... little heart applique to the rescue once more.