Terminated as Retaliation

I went to Ex. Dir. with examples and information on good work I had done, per California Labor Code 232.5.

The Ex. Dir. retaliated by accusing me of Breach of Confidentiality and asked me to resign. I was then called into Ex. Dir's office and a duty that I had been doing for over 2 years was taken away from me, and called on Saturday and terminated over the phone. I then received letter prohibiting me from gathering my personal belongings. Then a certified letter threatening to throw away my personal items away and cancel my checks and turn them over to Labor Department. I responded in the time frame with my physical address for them to send my personal belongings, now they refuse to do that too.

I don't know what they are saying about me, to justify not allowing me to gather my personal belongings, but it is not true and probably a defamation of my character. Can I sue them?