When in a child dispute case the evaluator has passed judgment against me because of my x husbands company employers wrote letters to the evaluator in his favor I want to sue the company?

Unless you could prove they made specific false statements that hurt you in the custody dispute, which would be libel, you have no grounds to sue. If you think you do have grounds, call the clerk of the court at your courthouse and they can walk you through the process. You would want to sue each individual most likely rather than the company. The company as an entity may not be At Fault and they have good lawyers.