I what to know, what happened to was Harassment or Retaliation and if there anything I can do?

I left my job after 12 years. I never got a warning until a new supervisor with only 2 months of work gave me a six-page warning without me knowing what was on, but the 5 Co-working knew it all. Soon I received another warning because a vendor who does not work with me said that I treated him badly all the time when we never worked together. On my last day of work after so much harassment, the supervisor told me she never liked me but she does like my assistant. What is the qualification for this supervisor has done, my assistant took my place with only 1 e six months in the assistant position. I have all the necessary documentation to prove possible retaliation.