How do I recover mentally and emotionally after being with a narcissist for 12 years?
That sounds like a very difficult and stressful situation to be in. I have worked for years with individuals working through narcissistic abuse and recovery. I use a book called "Power: Surviving and Thriving After Narcissistic Abuse" by Shahida Arabi. It is an amazing book that literally walks you through the entire process of understanding the abuse, how it has affected you, and what you can do about it. It also points out what to watch for in the future.
I believe the first question you need to answer is: "Do I want to make my marriage work?" If the answer is yes, there is a lot of work to do between both of you. If the answer is no, then I would recommend you make a plan and begin the therapeutic process of working through your grief.
This is not an easy decision to make, nor should it be. Please take care in considering what step you would like to make to move forward. When we act quickly, we can't weigh our options and can make decisions we may later wish we hadn't.
As a form of education on the subject, I will make a blanket statement about Malignant Narcissists--they thrive on your pain, and they enjoy it. To quote Andrea Schneider, LCSW, "Extreme narcissists (malignant narcissists and psychopaths) do deliberately and premeditatedly cause harm--and they enjoy it. They love hurting people as a form of narcissistic supply", and also states, "Extreme malignant narcissists or psychopaths are sadistic and beyond help devoid of any empathy or remorse for their actions." What we can learn from this, is that narcissists don't change, unless they can both see their wrongdoing, and have a desire to change that. With intensive therapy, recovery is possible, albeit difficult.
It is important to have all the tools and information so that you can make an educated decision. Again, please take care in making your decision for moving forward in one direction or the other. Good luck to you, and don't hesitate to reach out again.
Arabi, S. (2017). Power: Surviving and Thriving After Narcissistic Abuse. Thought Catalog Books.