Thanks for your question.
I'm very sorry to hear about what you're going through with your husband. While I can respect that you are willing to sacrifice your own happiness for the sake of your kids, that's not always what is best for everyone in the long run. You have to also consider the message that it sends your kids, and they are most likely to model their relationships after the ones that they see growing up. You may ask yourself what you would want your kids to do if they were in a similar situation, and that may help to guide your decision for yourself.
Overall you are going to be capable of being the best mother you can be if you are happy with yourself and your life. Ending a relationship can obviously be very complicated, but if the message that it is sending to your kids is that they should not put up with that type of behavior in their own adult relationships, that can be a very positive outcome.
Often times people who are narcissistic do not believe that they are contributing to the problems and that they are not willing to change or compromise enough to make a relationship work properly. If your husband is willing to work together with you to improve your relationship, that would be a very positive sign that things can get better. However, if there is no end in sight to this and you are already at the end of your rope, it may be best for everyone if you were to at least consider a seperation, if not ending the relationship.
I definitely wish you the best with all of this, and if there's anything else I can do to help please let me know.