Truth is a defense to Defamation. So you have no cause of action for defamation for anything that your former boss stated that is true. Furthermore, Defamation requires dissemination to someone other than you. Telling everyone you were suspended is not defamation, because it is true--you were suspended. As to the reasons, which you claim were false, you have no proof she said any of this stuff to anyone other than you, or even what she said exactly. Also, you should know that opinions are protected by the first amendment. For it to be defamation, it has to be a false statement of fact (not opinion) which damages your reputation--and even then, you have to prove that you suffered monetary damages as a result of the damage to your reputation by this person's defamation.
As to your wrongful termination claim, you should consult with a local plaintiff employment lawyer. Many give free consultations (check beforehand) so you would have nothing to lose for an assessment of your case.
We do not have an attorney-client relationship. I am not your lawyer. The statements I have made do not constitute legal advice. Any statements I have made are based upon the very limited facts you have presented, and under the premise that you will consult with a local attorney. This is not an attempt to solicit business. This disclaimer is in addition to any disclaimers that this website has made. I am only licensed in California.