My first choice would be to take out that block and replace it.
My second choice would be to put a piece of fusible web under it, fuse it, then creatively quilt over the rip, so it won't fray.
My third choice would be Bonash Powder, which is a fusible powder. I've used it for a tear that was too small to wiggle a piece of fusible under. I wanted to make sure the hole wouldn't fray. I sprinkled the powder under, fused it with a hot iron, then zigzagged over it. The original fabric was a dark plaid flannel and you can't see the tear unless you know where to look.
When using a seam ripper, try using it with the red ball point down instead of up. That way if your hand slips, you're less likely to tear a hole in the fabric.