(((Journey-Man))),

First, I can see you are a new member so welcome to Psych Central and the PTSD forum too.

I am very sorry that you had to experience a sibling that treated you so badly the way you described. It sounds like you have complex PTSD and that you have a history of feeling threatened and often the "empathy" you are describing comes from having a deep knowledge of what it feels like to be afraid and hurt.

It sounds to me like your brother had problems and may even be a psychopath or lack of ability to care or have empathy for others.

Here is a link you can read through that I found very helpful myself.

Complex post traumatic stress disorder (complex ptsd, pdsd, shell shock, nervous shock, combat fatigue), symptoms and the difference between mental illness and psychiatric injury explained