Brian James, a divorce mediator in Chicago, answers:
Yes, presuming the information does not affect the spirit of the mediation process or the agreements that you and your ex-spouse are working toward. However, if you tell the mediator something in confidence that they believe needs to be told to the other party, a good mediator will advise you to disclose this information during a session--and if you refuse, a good mediator should fire both you and your ex-spouse. Full disclosure is among the core reasons that mediation is effective and any break from total honesty taints the process.
Brian James is an experienced divorce and family mediator with offices throughout Chicagoland and Southeastern Wisconsin. He runs a mediation practice, C.E.L. and Associates. He can be reached at (312) 524-5829. View his Divorce Magazine profile.