Ladies, explain the purpose of a false divorce decree, if you can...?

I feel like I've had several bombshells dropped on me today.  My 2nd marriage failed because I caught my wife cheating on me, and thus I divorced her.  However, that's just part of the story.

While we were married and BEFORE I even filed for divorce, my wife was engaged to another man.  In fact, the two of them would be married right NOW, as I'm typing this except...

It turns out, the guy she was engaged to...was himself married.  SO to be clear...she was engaged to the other guy while married to me (and I had not filed for divorce yet).  HE was engaged to my wife while still married and living with his wife, and HE had not filed for divorce yet, either.

Now, she trusted this guy because he showed her his final divorce decree.  Only, the final divorce decree was fake, because at the time he showed her this document...he hadn't even FILED for divorce yet...and he was still married.

Now my question is...

WTF use is a false divorce decree?  I want the ladies to answer this one.  My line of reasoning is...

Marriage is a serious commitment, never to be taken lightly.  If you don't trust your future spouse with all your heart and soul, then you shouldn't even THINK about marrying that person.

If you have to insist on seeing a final divorce decree, then that is 100% proof that you don't trust your guy.  If you don't trust your guy, then it doesn't MATTER whether he's divorced or not!!!  (you shouldn't be marrying a guy you don't trust)  Am I right?