Depends on what country they are both in. If they are in different countries, nothing.

She could:

a) Preferred option, find a lawyer that deals with these things in his country of residence. But, not contact the lawyer. Just send a message to the ex to pass all contact through "Peado Sex Lawyers, Atlanta.....". He'll probably bottle it.

b) Just say fine, "I'll post the naked pics of him online"