Apart from every other consideration, the good of children should be the primary concern, and not overshadowed by any ulterior interest or objective. I make this appeal to parents who are separated: “Never ever, take your child hostage! You separated for many problems and reasons. Life gave you this trial, but your children should not have to bear the burden of this separation or be used as hostages against the other spouse. They should grow up hearing their mother speak well of their father, even though they are not together, and their father speak well of their mother”. It is irresponsible to disparage the other parent as a means of winning a child’s affection, or out of revenge or self-justification. Doing so will affect the child’s interior tranquility and cause wounds hard to heal.
Pope Francis, Amoris Laetitia, 245.