It does suck! Just be the rock for your children, so they can see a different perspective to the one your W and her family has. And, continue to vent here where it is safe. Your kids sound like they are pretty in tune with what's happening.
Take care.
Me:57 H:52 M:28 Got another lawyer last year and filed. D35,S/D twins28,D22 EA4/04 End? Who knows? "Life is like a mirror. Smile at it and it smiles back at you." — Peace Pilgrim