And finished. Well, almost - just the binding left to go.
I decided my best option was to un-sew a bit more, and cut out a rectangular section of border. I replaced about a 1 1/2" wide section with a new border section, stitched the borders back together, and quilted it. If you look closely, the piece is visible, but I think if you aren't looking for it, it's not obvious. And I'm confident that this section will stand up to use just as well as the rest of the quilt.
Now, on to binding!