Sorry this post is so long.
Is there any possibility of your attending a counseling session with your daughter? This might be a good avenue for you to bring up the subject of narcissism. However, be advised that most counselor/therapists are absolutely incapable of discerning a narcissist without having first experienced it, themselves. If your daughter has been in counseling as long as she's been separated (probably before), she needs a new counselor that specializes in domestic violence and abuse, period. There is also a book written by a narcissist about narcissism that you might want to just drop in her lap, one day, called, "The Malignant Narcissist." It can be found at Amazon.com. Sorry, I forget the author!
In the meantime, your haven of safety is helpful and healthy to the children, but it is important to understand that they have been conditioned to expect drama and trauma, at every moment. As insane as it may sound, there is always an element of surprise and expectation within an abusive environment - a sort of twisted feeling of "excitment," if you will. We know it's going to happen, but we just can't predict when he's going to go off. It took me a long, long time to become accustomed to peace and harmony and it only happened through determination and the help of abuse counselors.
The children need to be in counseling, as well. They have witnessed far more abuse and violence than you could ever imagine, in your wildest dreams. It is likely, probable, and an almost certainty that your daughter has been physically and sexually abused either in front of the children or behind closed doors. And, just because he perpetrated his sins against their mother "in private" does not, in any way, mean that the children were oblivious of their mother's torment. They don't have to see it to experience the repercussions.
Below are a few sites that will help you understand more about how an intelligent, self-assured person can become so immersed as the victim of a narcissist. Perhaps, you can choose some of the information, print it out, and give it to your daughter.
Unfortunately, she sounds as if she's horribly codependent (HE is the central focus of her life, divorce or not), in deep denial, and her counselor/therapist has dropped the ball. At this point - 14 months later - it would be reasonable for her to begin feeling outrage and anger at the sins that were perpetrated against her and her children, so it might be reasonable to suggest that she seek a new counselor.
"But, it takes so long to develop a rapport," is the weakest excuse for switching therapists - it's the counselor/therapist that makes us FEEL that is the one we need to find. A good counselor will empathize with their client, but they won't allow bullsh*t to hinder the work that needs to begin.
Best of luck to you and your family - keep up the positive energy, affirmation/validation for the children, and try to protect your Self from the negative energy that's produced by this warped relationship.
Sites:
http://www.healthline.com/galecontent/narcissism
http://www.mayoclinic.com/health/narcissistic-personality-disorder/DS00652
http://www.HowToSpotADangerousMan.com
site specifically for women
http://www.ptypes.com/narcissisticpd