School bullies are a difficult problem. I think you've done just right.
Never, ever initiate any contact with the woman for any reason. If she does something that requires a response, respond only in writing, certified mail, return receipt requested. He with the documentation usually wins the case if push comes to shove.
A neighborhood bully was seriously tormenting my grandson a few years ago. The bully was 2 years older, and about a head taller. My daughter worked through the process you have described with the school. I enrolled the kid in Tae Kwon Do, and today he is a second degree Black Belt. He is the smallest male in his class, but nobody messes with him.
