Getting geeky, for your definition of covert narcissism, you linked to diagnostic criteria from "Kim Saeedi". Her website gave no info on her credentials to propose those as diagnostic criteria. Google says she has a BS in Education. Dr Craig Malkin has a doctorate in clinical psychology, is a licensed therapist, and teaches psychology at Harvard Medical. He says a covert narcissist is a subtype of a narcissist and as such, the first step is to see if someone meets all the criteria for being a narcissist (DSM V). If that's too dry/dense to read and understand, there's "Dimensional Conceptualization and Diagnosis of NPD".
Your next steps are the same whether or not she's a narcissist or simply going through a selfish phase after years of resentment. Diagnosis would only matter if you both were interested in reconciliation.
