After a divorce, virtually every action by your former spouse can be viewed as an intentional irritant. If you have children and have joint or shared custody, you are likely to have a great deal of interaction. You may find your former spouse's tardiness or forgetfulness designed to irritate you and that may cause you to become even angrier.
You see they're arriving late, not because they were tied up at work or stuck in traffic, but because they wanted to push your buttons and tick you off. But anger is not a valuable emotion in this instance. For your children's sake, the less reactive you are, the better the lesson you will teach and they will learn.
Children in a divorce are very sensitive to their parent's behavior. You may believe that you mask it well, but they will sense your tension and stress, even if you are whispering on the phone to a friend, as your body language will convey your discomfort.
Remember, especially for younger children, you are central to much of their life, and even when you think they are paying you little attention, they are watching. And because they are likely to desire love from both of their parents, if you are constantly angry and upset with their other parent, they will pick up on that message, which they will have difficulty reconciling with their own love of that parent.
People worry how divorce will affect their children. When a six-year-old girl pleads with her parents not to be mean to each other, she demonstrates wisdom of what is harmful about a divorce; it is not the legal proceedings that cause harm, but the emotional frustration and anger that drive parents to be "mean" to each other.
Maintaining a civil relationship with your children's other parent when handling the many child custody interactions may be difficult, but exacerbating conflict and aggression are unlikely to make you or your children feel better.
Source: huffingtonpost.com, "After Divorce: Can You and Daddy Please Be Nice to Each Other?" Susan Stiffelman, September 21, 2015