I read an article a couple of days ago about private recordings under California law. I'll go back and see if I can find it. From memory - It takes more than just knowledge of the recording, it takes consent.
And the little tart muffin has 'said' he consented, but has shown no proof of it.....which makes not only the recording itself illegal, but I believe the publication of it as well.
Which makes HER liable for the recording and the consequences of it.
At this point, all we have are Stiviano's word for it that Sterling consented (and asked her to do it), and allegedly the word of the third party.
Remember that, depending on the circumstances, if you are aware something is happening, you may be deemed to have given consent without ever having said "I consent to this."