I'm so sorry for what you've gone through, this should never have happened to you as a young girl or anybody at all.
I think you have to reach out further for support ie beyond your family and I'm relieved to hear you are getting help from a therapist.
You will find more strength in others outside your family because to me they are very weak people indeed.
IMO they should have reported this behaviour to Authorities and then leave it in their hands. Who knows what else he has done. It's absolutely disgusting.
You can report this yourself and if you need a Support Person to go with you to Police then you can contact the Red Heart Foundation via FB. I couldn't have gone through what myself and my family have gone through without them. Most of this group's work is not public at all.
1800RESPECT are incredible for support. They can refer you to all sorts of help and they are an invaluable resource for you to access 24/7. You can phone them confidentially or you can give them your name so that each time you phone, their support is more cohesive and consistent. They are gems. Please phone them anytime you feel overwhelmed. Or any time full stop. It's no wonder at all that you're having panic attacks. Huge hugs darling girl, I am really feeling your pain right now.
You need alot of support to actually recover from this torment. The Blue Knot Foundation website pages may make you feel like you're not alone. There are stories there that may make 100% sense to you and in a weird way they are comforting.
I hope you don't feel so alone but this can be an extremely isolating experience.
Lots of love and healing