Divorce never finalized

[Tuscany55]

My parents went through a bitter divorce struggle 40 years ago. My father was awarded a divorce, and this was later appealed by my mother, and she won the appeal which voided the divorce. After this, there was no more litigation. He has a "wife" and 3 grown children now. After this length of time, are my parents divorced by default, or are they still legally married? Thank you.