Is a divorced woman sinful if she does not demand the implementation of the Hadd penalty for slander against her ex-husband who insults her, slanders her, and speaks about her honor, and is she rewarded if she does not respond to him for the sake of Allah and to protect her children?

You bear no sin for not demanding that the punishment for slander (hadd al-qadhf) be carried out against this man; for it is a right for you, not an obligation. If you forgive him seeking the pleasure of Allah, you will have a great reward; for pardoning an evildoer is among the best of deeds. However, if forgiveness leads to the man persisting in injustice, then it is preferable not to forgive at that time.