This happened to me. I told them that since ALL of my MANY years of performance reviews did not indicate the problem with my performance that what they were doing was effectively blaming the whistle blower and there are laws against that. I asked them how they felt about their chances with 10 years of nothing but good reviews to fall back on. They retraced their steps and started taking me more seriously. People have more power than they sometimes realize and sometimes they have less. Figuring out what position you stand in is often the hardest part.

I'm so sorry that happened to you. (((Hugs)))