KJ, You're asking your H to have transparency regarding the OW? Is this something he's willing to do? I get the impression that he's defensive when you bring this issue up.
As you describe, you and your H do have some connection, and that is likely a positive.
I think you're at a crossroads here. You can either continue to pursue like a journalist trying to get information about the status of his A, or figure-out how much connection you're willing to keep, and live in mystery about that part of his life.
When you say that you would no longer be his friend if he continued A, what does that mean? What is your definition of a friend?
CL
CL 53 W 54 M 20 yrs. 03'-09' Separation + Old Patterns + GAL 10-14' Piecing
"The Master allows things to happen. She shapes events as they come."