Hello Dechan: What an awful thing for your brother to say! I'm so sorry.

Your post struck a chord with me. I have often wondered the same sort of thing about myself. I have often said to myself (& even written a few times here on PC) I hope it could be said that I've been mentally ill my whole life. Because, if not, then that means I must have simply been a "bad seed".
I think, to some extent, having a "character flaw" or simply being a "bad seed" (as I've termed it) are just newer versions of old religious prejudices that suggested people could be "evil". At one time people believed other people were under the control of evil forces... the devil... or what ever.

Then later on, as society became slightly more enlightened, the idea of being "evil" in a religious sense went by the wayside & instead it became fashionable to say that a person has a "character flaw".
But really... all of these terms basically are just ways of explaining the outward manifestations of mental illness... if that makes any sense.

In other words, saying a person has a character flaw is just another way of saying the person has a mental illness. The unfortunate part of concepts such as "evil" or "character flaw" is, it seems to me, that these sorts of terms suggest that there is nothing to be done... no hope... whereas saying a person has a mental illness at least holds out the hope that treatment could be possible... even if the treatments that are currently available aren't effective.
So I guess what I'm suggesting is that the term "character flaw" is just another way of saying a person has a mental illness... which is... to me... simply a way of saying that the person's brain functions differently than most people's... perhaps in a way that is looked down upon by society... perhaps in a way that is less conducive to success in the everyday world. My personal opinion is there's no ghost in the machinery.

Our mental processes are simply the result of neurochemical activity in the brain which is influenced to some extent by genetics & to some extent by life experience. So I don't really buy the idea that there could be something such as a character flaw that is somehow different from & perhaps even worse than having a mental illness.
I know a thing or two about self-hatred.

(There's a lot I never talk about here on PC... a lot I don't even understand.)

I don't know about a spiritual solution. I'm not sure I even understand what that would look like. Since I don't believe there is a ghost in the machinery I'm not very conversant with spirituality in general. But mental health treatment has not really done anything for me either. That is why I have turned to the Lojong practices. I don't recall where the specific quote is located. But in one of Pema Chödrön's books she says that bodhisattvas are to be found among thieves, prostitutes & murderers. That being the case, I presume there's hope for me too.