Is your sister a psychiatrist?

No?

Stop listening to her. She's not qualified to diagnose depression. Depression is not a one size fits all kind of thing. Many people with clinical depression are able to function enough to hold down jobs and be successful. Others are at the other end and are completely non functional. It's a spectrum.

Oh, you say she is a psychiatrist?

Stop listening to her as she's a horrid psychiatrist!

As for the narc ex? I suggest you read up on personality disorders. You're applying real world logic to someone who lives by a different set of rules. (IME, that is, I've grown up with PD people.) This is crazy making. You will only feel worse.