Quit job due to false accusation of fraud

I have worked as Service Manager for an insurance agency in CA for three years. During that time, I have been subjected to verbal abuse and belittling by my employer. Other employees have come and gone, but lasted no more than 6 months on average. The last three employees he hired simply walked out during their lunch breaks, due to the hostile work environment. One tried to file for unemployment, but was denied.
I recently had a baby, and after coming back to work, decided that I would like to use my FMLA to take two weeks off. I brought the subject up to my then boss, and he flatly refused, saying that my job would not be waiting when I came back. (He only had 2 employees at the time) He then, out of spite, accused me of trying to file a fradulent claim with the insurance company that we represent. (I am insured with them and had recently been involved in a car accident.) The claim was completely false and had no basis. He not only accused me as an employee, but also as a client of his, while he is getting paid commision for having my business. I advised him that I would be reporting his unethical treatment of a client to his marketing representative with the insurance company, and he backtracked and denied accusing me. I quit my job over this. Now, he refuses to write me a letter of recommendation and I have reason to believe he is advising other prospective employers that I attempted fraud. Do I have any legal right for 1) the fact that I terminated my own position due to his accusation and 2) the fact that he is hurting my chances at getting another job because he is disclosing false information with no basis?

[randalljd]

If someone publicly says or writes anything factually untrue and it damages you, you indeed can sue for slander, libel, defamation, interference with business relations etc. -- or at least threaten to do so and give a warning.

The termination is not clear to me--he can fire you and you can quit. Not sure if there are illegal acts here--but clearly some very bad management exists.