There is a very good book - Boundaries by Thompson and McCloud. It has very Christian based principles but if you are not religious then the principles will help you per se
Can I recommend that book to you and it will give you a different perspective.
You will often hear from a narcist, After all, I have done for you and you will not do this for me. is typical narcissist behaviour. and blackmail and you have to put your boundaries in place The book speaks of what you will accept in your back yard - you have your principles and your boundaries and you will not cross them Now you can set those and if the other person will not accept your boundaries, then walk away until they do - and do not ever feel guilty.
The Book HOw to win friends and influence people was written by a son of a Baptist Minister and the principles are Faith-based but they are still very good
People who are narcissists have very shallow egos and they cannot bear to be criticised. Someone in my family gets into a vortex. a pity party and the only thing you can do is walk away - you have to keep your own treasures and your own self esteem for yourself and do not let anyone take that away from you