he's talking to you because he is miserable and has no where to turn, you are the closest person he's had and... it's payback time, what goes around (him cheating) comes around, the A's magic has dissolved.
It does make sense to talk about stuff before going to the mediator, that's what we did, the stuff we couldn't agree/figured out we left for the mediator. As long as you've talked to a L and know what you should get it's ok to negotiate with him before hand. Just don't give anything away unless he's giving something in return, think very well how it can affect you in any way.
You're doing great.
Be not afraid...I will repay you for the years the locusts have eaten Joel2
30something 2kids survivor of S, MLC, A, D I have peace in my heart, at last.