Incest Survivors Support Group
Incest refers to any sexual activity between closely related persons that is illegal or socially taboo. Consensual adult incest is very rare. Incest between adults and prepubescent or adolescent children is a form of child sexual abuse that has been shown to be one of the most extreme forms of childhood trauma. If you or a loved one is a survivor of incest, join the group...

You have nothing to be ashamed of. Keep telling yourself that. Look after yourself as you wish you'd been looked after when it happened.
Take it easy, let yourself work it out, process it. Do whatever you need to do, be that self pity or distraction.
It will get better. When you have finished processing it, you will feel better again. You know that. You've been here before and you've got better before.
I'm with you. We're all with you. You're not alone any more.
I say this because when i was 19, my brother tried to tongue kiss me. I wouldn't let him, but the emotional impact of him crossing the line was just huge. For one thing, I fell back on myself, and felt I couldn't trust anyone. I also remember a sense of shock. And since then, I've had plenty of nightmares where my brother takes advantage of me sexually.
Your feelings are valid, be kind and accepting of yourself.