Reporting without notifying the person?

Questioner

My girlfriend is involved in a difficult case with her ex-partner. Now this person is demonstrably committing libel and slander against me. I am considering filing a complaint. Now my girlfriend says that we have to tell her ex-partner if I am going to file a complaint. Now I have 2 questions: Am I really obliged to tell him this or can I file a complaint without telling him beforehand? The second: since it concerns her ex-partner, is my girlfriend obliged to do so or can she file a complaint against him and/or his new partner without informing him in advance? If possible, can you also indicate whether it is mentioned somewhere?

Lawyer

There is no duty to notify. However, if the police approach him in response to the report, the ex-partner will of course be informed of the report.