<p>I understand it must be difficult to be divorced, but you did chose to have children with your ex, so he must have some redeeming qualities. :)</p>
<p>You may get further by approaching him as the father of your children, and as someone who is always going to be important to them, rather than as " an idiot", no matter what satisfaction you get out of thinking of him that way.
Try to think about the big picture, stay away from petty insults.</p>