Gerber,Im sorry you feel such strong feelings about your place in the family.Family is often the ignition that propels deep hurt and self doubt.
I'll tell you Ive done some crazy,hurtful,inconsiderate things to some of my family members but there were real issues surrounding them.No you cant always blame family,or a disorder or our weaknesses for everything but you can try to see it as just LIFE and sometimes you get kicked to the curb and its your responce to it that really makes the difference.
I dont know if this advise is helpful but dont equate your personal value and self worth in comparison to family.
Most families have shadows it doesnt have to make you in the dark.