Legal Question in Criminal Law in California

I sympathize with your plight, but this is not a legal issue. It certainly isn't a matter of criminal law, which is the category under which you posted your question.

There are no laws, either civil or criminal, against having extramarital affairs. Even if there were, I'm not sure the limited contact your husband had with the office administrator would even qualify as an affair.

If you want to divorce your husband over this you can (in California you don't need to explain or justify your desire for a divorce), but the law will not help you decide whether that is the right thing to do.

Stepping outside of my role as a lawyer, let me point out that your husband rejected the other woman's advances and confessed everything to you when you confronted him. A lot of men wouldn't have done either of those things. That doesn't mean seeing the other woman and kissing her was right, but it probably does mean you're overreacting a bit. (To me, at least, considering criminal remedies seems a bit extreme.) This crisis is probably one you and your husband can get through together.

The experts you should probably be calling are marriage counselors, therapists and your clergy. This is the sort of matter lawyers are best left out of.

Good luck.