Is slander hard to prove in court?

Answer 1

Not if you have enough credible witnesses to this oral defamation, and can prove that it somehow harmed you (loss of business, etc). You may have to bring the witnesses in person, rather than by affidavit or deposition, so they can be cross-examined in court.

Answer 2

Yes it is cause in court you need evidence which you don't have unless you record it which then can still for forgery!