How do you defend against false allegations of abuse?

False accusations in a civil context are covered by defamation laws. There are other laws which cover false accusations in a criminal context, such as filing a false police report or even perjury.

If you make an accusation knowing it to be false, it is slander. Making the same statement in a media form is libel. However, both are usually covered together under defamation laws.

Defamation is a specialist field within the legal profession, and the difficulty of proving defamation varies. If someone is defaming you or falsely accusing you of a crime, what you need is an attorney, and the specialty of the attorney needed depends on whether it is criminal or civil law.