Anon can easily get a lawyer pro-bono, with contingency fee, who would nail a case like this to a cross.

In civil court, because she defamed him causing real and considerable loss of property, and psychological harm.

As for defending, Anon hasn’t really outlined any laws he might have broken…? Court for what? Just go to the trial and explain your side clearly and concisely: never a threat to anybody, cheating girlfriend made a false report.