OK. That makes sense. I'm fishin' here. How about.......
"Ex, we have two kids who are struggling right now (son especially) and even though our marriage ended, our responsibility to these two great kids didn't. The school said they wanted us to present a united front, and they were disappointed about the message it sent that we were not able to comply. I'm committed to setting aside any differences we have to focus instead on meeting the needs of our kids." What are your thoughts?"
"Always go straight forward, and if you meet the devil, cut him in two and go between the pieces." - William Sturgis, clipper ship captain, 1830's.