The problem is he has no clue about this and my wife and myself are having some serious doubts.
Sounds like it bothers you he is in the dark. And it bothers you that GF stated he existed, but did not state that he was in the dark about it all. So basically GF put you in the position of being her cheating partners.
You could talk to GF to get that straightened out, if you desire honest relationship with all parties. Otherwise you can walk away if she wants to continue in that fashion.
It's not a fun position to be in or fun to feel. I'm sorry.
You can't control her behavior. You CAN decide how YOU behave though.