Finally, I understand.

NPD

As a psychiatrist was once heard saying “Ns are the bread and butter of the therapeutic enterprise, not because they so often seek professional help—they are too impressed with themselves to ever think they have a problem—but because they drive so many people around them crazy.”

Well, I certainly know I am crazy now.
I just wish I had known about this while I was struggling to deal with M. And had I recognized that J's lack of empathy was incorrigible, I would have been able to let her go right away. Now I know that there are people in this world who are incapable of caring about other people's personal feelings, and that these people cannot be reasoned with.

Persons with a destructive narcissist pattern cannot see the behaviors and attitudes they exhibit as you and others perceive them. They are unaware of the impact on you, and are well defended against knowing. Further, your attempts to make them aware or get through to them will fail, and will be perceived as threats to their core essential self. This will bring out their defenses for protection. The defenses are likely to be hostile, aggressive, strong and immediately available to them, so that they are able to attack and mount a strong counteroffensive in a nanosecond. You generally do not win or make any headway, and can find yourself in a worse position than before.

So how do you win?

You don't. Let them go.

Now I'm the first to admit I've got a personality disorder too.

"Hi. My name is Ben and I have dependent personality disorder."

I think this combination between an NPD and a DPD must be pretty common, as DPDs would be drawn to NPDs for their "self-confidence" and NPDs enjoy the power they have over DPDs. And it must also lead to a lot of pain, as it did twice in my case.

While I'm trying to deal with my own problems, I find it so frustrating that those two people I loved so much (and still do) will forever refuse to deal with theirs.