Why not just carry on as if you've known all along .... That'll drive him nuts trying to figure out how much you knew and when. And also means that you can openly acknowledge the reality of the present.
On BD H52, W50 T27, M26 S21, D23 BD-9-Mar-16 D-15-Jan-18 Final-19-Apr-18 I am a storyteller. The story may do you no good. But a story is never for the listener. It is always for the one who tells