Good. I want to help in any way that I can.

I'm sorry, I think that I spoke a little too quickly here. Most colleges do indeed have counseling centers and the staff there will counsel students. However, colleges often limit their counseling for students. If a student wants to meet for more than a certain number of sessions, the counselors often refer the student to someone off campus.

With regard to RAINN or other counseling ideas: I have two things in mind. First: I accept and encourage that you are competent to make your own choices about whether or not to seek counseling through RAINN or somewhere locally. Second: I want to encourage you, in making that decision, to listen to yourself carefully, to be kind and honest with yourself, to keep in mind that you have suffered extended, grievous mistreatment.

The facts that your brother has a different genetic background, as well as FAS, are suggestive. FAS, which can be quite harmful, is discussed in some detail in wikipedia. I understand that a number of addictive behaviors have a strong genetic basis, though I do not know specifically about pornography.

I think that the causes of his anger are of interest, though, because thinking about them dispassionately inevitably reveals that his actions were shameful and wrong. For example, an addiction to pornography and images of violence need not and must not entail the humiliating imposition of those images into the mind and private spaces of one's younger sister. Nor can anger over any aspect of one's life ever justify or explain the systematic, seemingly endless mocking and sexual abuse of one's younger sister.

He, not you, had problems that were not treated or controlled properly. He, not you, behaved shamefully. People were wrong to abandon you, to disregard and overlook your complaints and earnest entreaties for help, while protecting him and downplaying the significance of his actions. Your pain, embarrassment, shame arose extrinsically, not intrinsically.

I'd like to say two things about your parents' role.

First: We have a daughter who, like you , is our youngest, and we have several sons. Our sons could never ever in their remotest dreams imagine getting away with doing anything sexually abusive or otherwise patently evil to our daughter. It was completely wrong to expect you to endure that, and it was mistaken to think that making you endure that was actually benefiting your brother. It wasn't.

On the other hand, here is something that took me a long time to understand, and may help you in understanding your parents. First, a little background. My mother was a narcissist and an alcoholic. Her narcissism and alcohol abuse caused many many problems in my childhood. I was an only child, and I was abused emotionally (not sexually). It took me many years to overcome the resulting problems, and in fact some of them I still have with me.

I came to realize, though, that in her own way, my mother loved me. Her love was like a stunted, diseased tree that can nevertheless still offer some modest shade. She did many wrong things to me and regarding me, but she still loved me, perhaps as much as she was capable of love, and meant well for me. Our family life, then, was a kind of tragedy, in which her flaws made it impossible for me to be close to her. When I think of her now, it is not with love, but it is with a degree of understanding.