The fact that this story doesn't make me unhappy, though, indicates that I'm leaning toward the good riddance side.
She allowed the law to set his punishment for years. What he said to this mother could be considered a threat.
As a mother myself, my first thought would be that he meant my daughter even more harm, if not that very day then at some point in the future.
The law was obviously not capable of protecting this family from the bastard rapist and she was forced to defend her child in a desperate way.