Yes, this is an invasion of privacy.
This answer is offered for informational purposes only. It is not offered as, and does not constitute, legal advice. Laws vary widely from state to state. You should rely only on the advice given to you during a personal consultation by a local attorney who is thoroughly familiar with state laws and the area of practice in which your concern lies.
This is a matter of state law and requires a review of California law (I am a Virginia attorney and cannot advise on California law). Having said that, you may have a blackmail claim if he threatened to post the pictures unless you do something. Consult with a California attorney for possible actions.
[This communication is intended as general information and not specific legal advice, and this communication does not create an attorney-client relationship.]