A narcissistic ex often insists on remaining in the life of a former spouse or lover, and can therefore continue to present problems for some time after a relationship ends. If in the process of ending a marriage with a narcissistic person, it is considered of the utmost importance to take full advantage of the legal system to help end the relationship safely. People who have children with a narcissistic ex can learn coping skills to help them interact with the narcissist calmly, while maintaining personal boundaries. People with narcissism usually care only about themselves, and can be unreasonable, selfish, emotionally volatile, and manipulative, yet they're often incapable of recognizing their own behavior as flawed. Thus, it's generally important to avoid engaging emotionally with the ex, to constantly reinforce strong personal boundaries, and to flatter the narcissist where necessary.
It is considered common for narcissists to launch personal attacks against their victims. When dealing with a narcissist, ex or not, refusing to respond to personal attacks can help defuse the situation. Many narcissists do not seem to understand why their victims respond to personal attacks and abuse with feelings of anger, pain, or betrayal. Responding with equally strong emotions of one's own can have the undesirable effect of making the narcissist feel validated and encouraged in his behavior. Experts generally recommend responding to the narcissistic ex's volatile emotions with detachment and calm, perhaps using a statement such as "You're obviously very angry."
Many narcissists will respond well to a statement that seems flattering, since they generally think of themselves as beyond reproach. Rather than engaging with the narcissist emotionally, try using flattery to gently suggest a change in behavior. Statements that contain flattery, such as, "You're so generous, I know you don't mind sharing the cost of Billy's school clothes," can help to make the narcissist feel validated and secure, thereby minimizing emotional volatility and improving the chances of cooperation.
Even if maintaining an air of calm in the face of narcissistic abuse doesn't stop the behavior, many experts believe that it can stop the behavior from escalating. Many people with narcissism fail to recognize or respect the basic needs of others. A narcissistic ex may be very willing to disregard personal boundaries, since he will generally believe his own needs, desires, and feelings are far more important than anyone else's. For this reason, dealing with a narcissist often means stating and re-stating boundaries repeatedly.
You should generally expect to have to reiterate your personal boundaries to a narcissistic ex at each new meeting. Most experts will advise identifying a set of consequences that will occur if the narcissist crosses a personal boundary, and sticking to these consequences. While it probably won't change the narcissist's behavior, it can at least offer psychological protection against it.