From her job she knows the financial impact of divorce. That doesn't mean she doesn't want an ideal outcome for hers.
When I read your posts I hear "Oh, yeah? Take THAT!" when you respond to her requests. As hypocritical as this seems, you can DB your way through divorce. Being conscientious but maintain your stance works in your favor.
W: I can't believe you're going to deprive our children of their home and the stability it signifies by not paying what is(or what I consider to be) fair.
FL: I understand how you can feel this way.
W: Divorce is difficult enough without the kids suffering too. They are the innocent ones in this process.
FL: You are absolutely correct. It is difficult.
W: You realize their standard of living is going to be severely impacted.
FL: Divorce effects everyone.
You have nothing to prove. You love your kids. GET that bigger apartment so you're spending more on your financial affidavit. Live realistically. Otherwise being frugal WILL work against you.
*hugs*
PS.. ask the mediator if the amount recommended changes if you go to a larger apartment that fits the needs of your children.