The biggest problem with coparenting with a narc is protecting your children from the abuse. Don't make excuses for your ex's behavior and never badmouth them to your children. Answer your children's questions (and there will be questions because narcs love to spread lies and gaslight to look better and make you look worse) calmly and firmly. Be prepared to say, "I'm not sure why he said that, x is true." Validate your children's feelings as much as you can without being upset. Narc parents love to bring on the drama. I'm sorry that you and your children have to live through this. Be safe,