Well - you can help them by stopping "horribilizing" this.
Your ex has an OW (big surprise - they always do) and is living 30 mins away (NOT an insurmountable distance - it's not like he moved to another state or country, like some guys here).
He may be temporarily insane and selfish, but it doesn't automatically follow that he'll always be a bad parent. Try to separate out YOUR abandonment and pain, from what's happening between your kids and their dad. You should be encouraging them, letting them know their dad still cares, and encouraging their dad to see them. I know, it seems unfair and stupid that you have to be the bigger person here - but for the sake of your kids, you DO.
