Some people say that noone else can tell them anything as bad as they do themselves — and that therefore, they are more impervious to verbal attacks.
I recognize about half of that in myself: I tell myself a whole slew of nasty things on a regular basis.
It doesn't grant me any extra strength, though — instead, someone else telling me the same thing confirms the nastiness to my mind, and breaks me down even further.
And it really doesn't matter that much about external reality or indicators either. Clearly, my own self-estimation is faaaar better than anyone elses, so whenever I get positive indicators from outside, they can safely be disregarded as clearly delusional and irrelevant.
This way I end up thinking…
…that I am lazy.
…that I am stupid.
…that I am ugly.
…that I am fat (and that this is bad).
…that I take up too much space.
…that I offend strangers around me.
After decades of this, with over one decade spent concretely aware of my suffering from a disorder (and thus this not actually being a normal state of affairs) I am slowly getting to the point where I can recognize that this happens, and can describe it with a tiny bit of distance — even be sarcastic about my internalized script. It doesn't make the self-hate go away, but I start seeing how it is a script that plays itself, rather than a completely objective assessment of reality.