A mediator is there to do just that, serve as a bridge between the two of you. If he/she is doing the job well, the mediator will not take sides. In mediation, they are not legally bound to either side, but to facilitate a mutually agreeable agreement.
Keep your cool, NDDT. Be prepared, but don't go in expecting both mediator and W to try to screw you.
BD
My latest
Me: 36 W: 35 2 D: 9 and 5 T: 16 years M: 12 10/4/06: Bomb 10/5/06: Ended A 4/22/07: ILYBNILWY