Although the number of persons in this situation are statistically low, situations involving a narcissist are among the most challenging.
A narcissist is someone who has an idiosyncratic view of the world and relationships. It is as if they have a very negative self-image, causing them to always defend themselves. They view almost all incoming information as adding to that negative self-image. To survive then, they attack back, believing others to have attacked first. To add, they are forever working to bolster their self-image and become preoccupied by seeking to be perceived as better than others.
This is happening beyond awareness for them, so trying to explain either their issues to them, or one’s intention or behaviour towards them, is often futile. Some believe this personality to be an outcome of either abuse or neglect in early childhood, while at the same time either being indulged or being left to do mostly as one wishes for themselves.
A common feature of this person is to blame others for any misfortune, and given they feel things intensely, they are apt to take their emotions as facts. When facts don’t actually fit their emotions, rather than self-examining, they are more apt to distort the facts instead to then make sense of their feelings. Thus, narcissists are seen to be highly manipulative and angry, although when wanting to appear better than others, they at the same time can and will project a charming disposition. This adds to an impression then, that they are not the source of the problem when really they are, and that the other person, distraught by the behaviour of the narcissist, is therefore the one with issues.
Divorcing/separating from a narcissist then can be quite challenging. They may seek to emotionally and/or financially destroy their former partner, acting out their rage for perceived injustices towards them, essentially not facilitating their inflated sense of self. When children are involved, they truly can become their pawns, used as tools to extract more revenge. If a child sees through the behaviour of such a parent though, the child may actually be rejected.
Narcissists may fight without end at court, and it is unlikely that they follow court orders, believing they are above the judge or others who hold positions of authority. A negotiated settlement may be more fruitful and is more likely to be followed.
If you are divorcing/separating from a narcissist, make sure your lawyer has experience with this. Do also consider adding a divorce coach for yourself. That would be a person with knowledge, training and experience helping people to cope and mange in these circumstances.