It sounds like to me that whatever you say, it will be seen as a personal attack. Just keep it business. You can't be responsible for your XW's emotions. If she throws a fit, it's her problem, not yours. You're just trying to take care of your kids as per the divorce agreement.
Mr Nice guy or not, stay cool and take care of what needs to be, morally and legally.
Formerly SGfan M:38 W:33 M:8 yrs T:10 yrs Bomb: Dec '08 Separated: 4/18/09 Divorce: 8/28/09 XW Affair began: April 08