lostraven It's not worth responding in many cases to that. No amount of telling the truth even if you know every word in the game won't convince them. It's like they get an idea and that idea becomes something they are convinced of without any actual basis for it. Then when we try to tell them what the truth is, they often get defensive and to them, it feels we're attacking them when we're really not. It's not something that we can fix or help.
Best thing to do is to make a firm, very firm statement as clearly as possible and stick to it. If they go off the rails, point that that statement once and firmly state "That's the truth. I'm part of the game and I know." Then don't respond and let them fix themselves (if they ever can or will) since we obviously can't do it.