You cannot go dark on the kids. You are their Father!!!!
You can contact W and set a regular schedule for visits and Skype sessions with your kids.
Then all of your communications with W are to be focused on the kids as necessary. Don't try to use the kids to communicate with W. See what I am saying here?
Keeping the road home paved smooth, to me, means not guilting/shaming (as Ad said above) the WAS, holding on to your scorecard and resentments, engaging in righteous indignation, and showing true forgiveness. You focus on her good qualities instead of past mistakes.