Okla. Stat. tit. 12, § 3318

WAIVER AND PRECLUSION OF PRIVILEGE. A. A privilege under Section 17 of this act may be waived in a record or orally during a proceeding if it is expressly waived by all parties and, in the case of the privilege of a nonparty participant, it is also expressly waived by the nonparty participant. B. A person that makes a disclosure or representation about a collaborative law communication which prejudices another person in a proceeding may not assert a privilege under Section 17 of this act, but this preclusion applies only to the extent necessary for the person prejudiced to respond to the disclosure or representation.