At one point my W had stated that she really hadn't made up her mind regarding the D until july 1 when the exposure bomb detonated. I pointed out that prior to July 1 she was knee deep in an EA, talking about dating while living under the same roof, and that she told me before the EA bomb that she had pretty much decided on D. Plus her approach to MC was just exit strategy. So no thank you. That little fairy tale may be something you tell your friends and family but I'm not going to let it pass in this venue. Not much to say.
BINGO -- well defended.
Your mediator should be able to suggest some other "50/50" type custody arrangements that are more traditional. I do think stability for the kids during the school week is a plus, but then again there isn't anything ABOUT your wife's current lifestyle or decision-making that exactly screams out "stable", either.