Divorce records are kept at a county level for the state needed. Many counties have their records online but only as far back as the 1990's. I usually tell people to start in the county where the person was residing at the time.
Dear Ms. Barry,
Thank you for posting your request on History Hub!
In Oklahoma, marriage and divorce records are maintained and issued by the Clerk of Court in the county of issuance. For a listing of counties, please use the FamilySearch Research wiki for Oklahoma.
We hope this is helpful. Best of luck with your research!