POC Employee Harassing Caucasian and other POC Employees What Would you do?

My work is a nice mix of backgrounds, and we have enjoyed diversity and harmony until recently. I have a female POC employee who has experienced situations of racial discrimination and many negative personal experiences at other jobs and in her home life. Unfortunately since starting here, she has been targeting caucasian employees whom she believes are not suitable for the work. She insists that one in particular is unkind and treats her differently, that there is something wrong with him and she zeroes in on anything this person does that she deems is wrong (even if it isnt) and insists that conversations in writing and in person have been disrespectful to her. However the conversations that she complains about are conversations that others including POCs are in or have witnessed and they report that this person isnt acting out of sorts against her in any way. In fact they have gone to the employee she is targeting to make sure he is okay because of how she lashes out at him. She is also overriding and undermining another employee until they shut down and cried. She insists that situations, many of which I have been witness to went differently than it has. She has gone after and said rude things to other employees that are also POC and we have complaints from those employees too. She gets very aggressive and visibly angry when ever someone has a different opinion than her and has no tolerance for anyone other than those that agree with her completely. She will lash out, restage events and details that puts anyone that she disagrees with in a bad light. Every one of her coworkers except one have complained that they arent sure which of her they are going to get in a day as she fluxuates from very friendly to very callous, to very mean and suspicious of everyone. I have to let her go for bullying. I have complaints from caucasian and from POC employees about how she talks down to them. How would you handle this? What type of documentation would you make to protect the company from a wrongful claim of discrimination? I am very cautious with this employee and am working on an exit strategy for her. I cannot see any option or have any idea how to relay that it is her actions that see her out the door as she believes she is being discriminated against when we have counseled her on appropriate behaviour and how to act kind in the workplace. She backslides after a day or two of being nice and seems worse than she was before each time.