How do we go about finding out if his ex ever got a divorce from him?
Do we have to find out where she lives, SS# or what all info?
They were married in Virginia & we think she still resides in VA, and he has moved in & out of VA over the years. We checked the county records & they can only check back so far & didn't find anything. They did have a child together, but she is 30 yrs old, so shouldn't be any issues. He doesn't have any assets so those shouldn't be any issue.
Any suggestions?

If he is in doubt, and can not find her or prove there was a divorce, he should file for divorce, there will be some requirements as to seaching for her, but in the end, the judge will award he divorce.