Actually, the spousal privilege under OK law is much narrower than what you describe. There are actually two different types of spousal privileges in American law. One is the "spousal communications" privilege and the other is the "spousal testimonial" privilege. In general terms, the testimonial privilege applies more broadly and allows a spouse to refuse to testify about both observations (such as witnessing their spouse commit a crime) and communications (such as discussing a crime that the spouse committed). However, the communications privilege - which I am fairly certain is the only privilege available under OK law - is not nearly as broad. Basically, the privilege only protects a spouse from testifying about confidential communications that occurred between two spouses during the course of their marriage - they still must testify about anything/everything else. While the communications privilege generally survives the dissolution of a marriage, I cannot recall coming across a state that protected communications that occurred prior to the marriage. (This is another difference between the two types of privileges, as the testimonial privilege will often protect spouses who are married at the time of trial, but who were not yet married at the time the observations or communications in question occurred.)
I hope that I explained that somewhat clearly. Please feel free to ask a follow up if any of that was confusing.
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Also, while I am at it, I thought I would dice up the rule into a more understandable order -
The general rule is provided in part (B):
The definition for confidential communication is provided in part (A):
Part (C) just explains that either the accused spouse can prevent the witness spouse from testifying about confidential communications, or the witness spouse can themselves refuse:
And finally, part (D) just provides an exception to the privilege otherwise applying (which largely deals with domestic violence type situations):
http://www.lexvisio.com/article/1713/1400/0-1000/1/dA/Oklahoma+Evidence+Code