Is it an infringement of reputation or something else?

First of all, if the plaintiff can prove that the fact of reputation damage exists, the court should file a case.

Second, if the plaintiff can prove the fact of reputation damage, you should bear the responsibility.

Third, what is your counterclaim?

Fourth, anyone with mental health and normal expression ability can be a witness. The size of the evidential force is not simple and can be explained clearly. If it is supported by other physical evidence, it has strong evidential force.