Malignant Narcissists will never apologize, if they do, please understand, that is the mask they are wearing for you to continue to get supply from you. They feel no remorse. Narcissists are Predators!
You've probably tried everything you can think of to help this person, but in the end we have to come to an acceptance that is an almost impossible task. It may happen but only if the narcissist becomes so downtrodden and they wonder why.