Co-parenting is challenging, for sure. But there are some personality disorders that make the commitment to raise your children collaboratively -- but separately -- even more difficult. For example:

1. Narcissistic Personality Disorder. Narcissists have an inflated sense of self-importance and lack empathy for others. They are often referred to as arrogant, self-centered, manipulative, demanding, and vain. As co-parents, these individuals often feel superior to their counterparts. A hallmark of this particular personality disorder is insisting on getting one's own way -- regardless of how it impacts others. Because narcissists have little or no ability to empathize with others, they have a hard time recognizing that their choices and behaviors affect other people -- even their own children. As a result, it's difficult to reason with a narcissist or even coach them to see the situation from someone else's point of view, which makes co-parenting together extremely difficult.
   
   Tips for Co-parents: In this situation, one of the best things you can do is file a parenting plan with the courts. This legal document would outline all of the agreements you've made with one another as co-parents, from your everyday parenting time routines to how you'll spend each holiday. This decreases your ex's ability to use manipulation to get his or her own way. For more information about narcissism, read Narcissistic Personality Disorder.

1. Borderline Personality Disorder. Individuals who suffer from Borderline Personality Disorder relate to others based on long-standing patterns of behavior (as opposed to what's happening here-and-now) and frequently experience intense, turbulent emotions directed toward themselves and/or others. In addition, they often revert back to patterns they experienced in past relationships instead of embracing interactions in the present. Parents who exhibit these characteristics may accuse their co-parents of not caring enough or may instigate push-and-pull games aimed at forcing the other parent to "prove" their commitment again and again. Individuals who suffer from this condition are often referred to as "unstable" and experience difficulty maintaining interpersonal relationships.
   
   Tips for Co-parents: If you suspect that your ex has Borderline Personality Disorder, make an extra effort to set healthy boundaries with him or her. When you sense that an argument is brewing, train yourself not to get defensive or over-explain your point of view. Instead, stay calm and try to remove yourself emotionally from the situation, so that you don't get caught up in your ex's turmoil. It may also be helpful, at times, to defer important conversations or have a neutral third-party present when your ex is particularly upset or angry. To learn more about Borderline Personality Disorder, read What is Borderline Personality Disorder (BPD)?

1. Antisocial Personality Disorder. This personality disorder is most often exhibited in the habitual manipulation, exploitation, and/or violation of others. Antisocial personality disorder often accelerates into criminal behavior and, particularity when children are involved, should never be ignored.
   
   Tips for Co-parents: In situations where your ex continually exhibits signs of Antisocial Personality Disorder, it can be helpful to document your interactions. For example, write notes in a bound, dated diary about each conversation -- via text, phone, or in person. This will serve two purposes: First, in the event that you feel threatened, it will help you decide if/when to take further action, such as getting a restraining order. Second, it could provide the courts additional information in the event of a custody hearing. For more information about this condition, read Antisocial Personality Disorder.
2. Bipolar Disorder. Characterized by intense mood swings, bipolar disorder is also known as Manic-Depressive Disorder. Individuals who suffer from bipolar disorder may be extremely jubilant and driven one day, and then extremely depressed and despondent the next. Parents who experience this condition may have difficulty maintaining a regular co-parenting schedule or exhibiting sound, reasoned judgement -- particularly when they're in a manic state.
   
   Tips for Co-parents: If you suspect that your ex has this disorder, it may help to keep a journal about his or her highs and lows. If you have a decent working relationship, you may even be able to share your observations with your ex and encourage him or her to seek treatment. If your ex is on medications, it will be important for him or her to continue treatment in order to manage the symptoms of Bipolar Disorder. To learn more, read About Bipolar Disorder - What Is It?

Finally, remember that you're not alone. Call your community mental health clinic or 2-1-1 for help in your area. You may find that even though your ex is the one suffering from a mental illness, you (and even your kids) may benefit from counseling, as well. A well-trained counselor can help you develop even more condition-specific strategies for dealing with your ex's personality disorder so that you can continue to raise your children together.