The principal exception to the two-party consent laws (Penal Code 632), is found in Penal Code 633.5, which provides: "Nothing in Section 631, 632, 632.5, 632.6, or 632.7 prohibits one party to a confidential communication from recording the communication for the purpose of obtaining evidence reasonably believed to relate to the commission by another party to the communication of the crime of extortion
, any felony involving violence against the person, or a violation of Section 653m. Nothing in Section 631, 632, 632.5, 632.6, or 632.7 renders any evidence so obtained inadmissible in a prosecution for extortion, kidnapping, bribery, any felony involving violence against the person, a violation of Section 653m, or any crime in connection therewith."
In short, an individual has no reasonable expectation of privacy in a conversation wherein the individual threatens the other party to the conversation, with a criminal act identified in Penal Code 633.5.
I don't know if this helps you, but as you mentioned that the other party has made certain "incriminating" statements, if any are related to the commission of a crime against you, then you would be entitled to record the conversation without prior disclosure to the other party.
The presence of video cameras in a room do not remove a person's reasonable expectation of privacy in an audio conversation, because it is commonly known by the general public that video surveillance cameras do not record audio signals. However, if it is known within your organization that the video surveillance cameras do record audio, then that would destroy everyone's reasonable expectation of privacy, to the extent that they have advance notice that conversations are routinely recorded within your offices.
Other than that -- no audio recording is permitted without advance consent of all parties.
Hope this helps.