I think ladyscribblers idea of writing responses/keeping track of lies is a good one.
I agree that keeping your emotions in check (not responding, interrupting) are the most important things, (almost impossible not to react) I am glad you wont be in the same room.
The biggest lesson I learned from treading the mess, was he CAN NOT SEE in your head. Don't let him. Get ready to become a great actress. You can be jumping out of your skin (ON THE INSIDE) and still put forward that you have it all together on the outside. (YOU CAN pull it off.) Don't give him the satisfaction or the ammunition. I know its hard. This is just one part. This first meeting will be over by the end of the day. Hang tough.