I understand you have a mediator, but I'm thinking it might be wise for you to at least consult with a few lawyers. I would check on these calculations the mediator came up with. My guess is this mediator has been hired by your wife... so basically the mediator is working for your wife? Since I don't know too much about mediation please, those of you with experience, correct me if I'm wrong...
I understand you want to save your marriage, but I think it would be wise to look very carefully at financially protecting yourself if this whole thing goes through.
There is no arriving, ever. It is all a continual becoming.