The Little Shaman is a spiritual coach & specialist in cluster B personality disorders, with a popular YouTube show and clients worldwide.
Narcissists are a reactive bunch. They get really mad, they get really excited, they get really depressed, they feel really stressed and they are overly-sensitive. Part of this is because they are often underdeveloped emotionally. They are not always able to regulate their emotions or their reactions. Their control over these things is like a child's would be. Emotions just sort of run wild, unchecked and out of control. So every feeling is way out of proportion to the situation. Even those who have perfected a calm, cold or callous exterior often experience this internally, and if you watch them carefully, you will probably see it.
This inability to regulate their own emotions and reactions is the reason you see the rage and hysteria that is common with pathologically narcissistic people. LIke a child throwing a tantrum, they feel that they just cannot control their feelings and more importantly, they don't even think they need to try. This inability to regulate is also why you see the despair that they are often known for. Everything bad that happens is the end of the world. It's the worst thing that ever happened and will end in catastrophe - every single time. Those that do not react outwardly have often learned that showing emotion is weakness, so they keep a very tight lid on it but if pushed hard enough or stressed badly enough, they will often over-react horribly, leaving people shocked at the depth of their rage or the degree of their instability.
Recent studies have shown that people with high levels of narcissism actually feel stress more intensely than those that do not have high levels of narcissism, and this is likely another result of their difficulty with managing and regulating their emotions. It also explains why so many narcissists cannot function under even normal, every day stresses. Many narcissists simply fold up under stress, or when something goes wrong. They just can't deal with it. They cannot regulate their feelings of stress and they have no real coping skills so they lash out or do things that hurt others in an attempt to make themselves feel better. It's a primitive way to live and it doesn't work very well for them in the long run but it makes them feel better in the short-term and that is all they really understand or care about.
For pathologically narcissistic people, life is nothing but an endless attempt to feel better. They spend their entire lives trying to ignore, deny, evade and avoid their emotions but of course, they can't. They are consumed by them, because they have never learned how to manage them and because denying something only makes it more powerful. When they can no longer retreat to denial, there is often an explosion of all of these repressed feelings. There is blame, there is projection. They do everything they can to protect themselves from these overwhelming feelings they are trying to avoid and if they can't deny them or avoid them, they seek to blame them on others. When there is no one to blame, no one to feel better than, no one to prop them up, this is when we will see decompensation. It is the result of the walls coming down and those feelings finally catching up with them. They cannot be avoided any longer and the narcissist simply crumbles under their weight.
Think of the shock and pain you felt when you finally had to face that the narcissist was not who you wanted to believe they are. Imagine being forced to see that about your entire life, and worse, your own self - with no way to make yourself feel better or manage the situation at all. It's tantamount to discovering that you have been being a serial killer in your sleep. This is what they are trying to avoid. It doesn't make their behavior OK or acceptable in any way, but it does help with understanding how dedicated they are to their illusions and false images. It's very important to them. In fact, you could say it is the most important thing in their lives.
When dealing with narcissistic people, you are usually dealing with a very powerfully reactive person - whether you see it or not. Feelings guide their behavior and all of their decisions, one way or another. This is the key to dealing with them: remembering that will help keep you grounded, so that feelings are not guiding your decisions and behavior. Once you can control that, you take their power away.