Helltoraise,
I was raised in a family that mirrors yours and Lillamy's. Love that -the part about the sisters bossing each other around! That's exactly what we do in my family too!
Throw in the mix a raging tempermental dictator father, and a drunk righteous minister mother, and you can imagine just what I grew up with, a large family too.
For us, it is simply best that we keep our meetings limited. Holidays are enough to set any of us off balance for a week. Each of us has our issues that are clear as day (supposedly) to the others, as there is judgment there.
For me, having limited contact is the only way for now.
So how can you overcome these voices in your head telling you that you are bad or worthless?
I think you have to really delve into that. Examine it deeply. Guilt doesn't work on us, if we don't actually feel guilty! So why do you feel guilty? Why do you feel worthless? Catch yourself in mid-thought on these things, and then look at them as rationally as you can, as objectively as you can. Observe where you might improve, and learn to discard that which is invalid. It's not easy, not easy at all. But self-examination is the only way to overcome this.
Can you grow out of the identity that you feel you were given? Yes. You can create your own adult identity that can be quite different from this bad one you describe. It's not done with some blazing forth energy though, it's done with quiet reflection and balanced logical thinking.
The thing is, it's nearly impossible to do that if you are immeshed in constant drama. You do have to remove yourself somewhat.
So you're off on your own I presume...and when you sit in your own space, can you listen to the quiet when alone and feel ok with yourself? I'd start there. Get to that place that when you are sitting alone in your own space you are ok with who you are. Journal, reflect, and do of course what you need to get accomplished for your own self-esteem.
People in families like this need to be able to be comfortable alone in their own space, first. Then they need other positive influences and people that are not part of the dysfunction of the family. It's a never-ending process, but with each freedom you give yourself, you feel yourself stronger and more stable with who you are.