Wrongful accusation in workplace re: oppression and racism

[JW2009]

What is the name of your state (only U.S. law)? WA
Our HR manager dropped the ball in a big way on a major HR initiative. I work in another department but was involved in the project and had deadlines and deliverables that were mine to accomplish as part of the project. Long story short, she and I had a not-so-friendly conversation that from her side she claims was oppressive and from mine was, at worst, rude. Now management, claiming they are ill-equipped to handle this dispute, are asking for my participation in outside mediation with the person. No evidence has been produced by her evidencing her accusation that this was oppression based on my being white and she being a minority. If I comply with mediation, is this an admission of guilt? If I do not comply, what are the repercussions? What are my options? IS this something that will go on my record? (I've been told it is not, yet if it is workplace-ordered, my sense is that it will.) Are people allowed to make false accusations against another employee and hide under the guise of protected status without any evidence? Please help.

[eerelations]

Complying with the order to attend the mediation is most definitely not an admission of guilt. Attending the mediation means the following:

1. you're a good employee who wants to do what his employer tells him to do; and
2. you have a sincere desire to see this issue resolved.

If you refuse to attend the mediation, your employer may legally fire you.