I'm sorry you went through that too! That degree of sexual assault and everything that went with it - being kidnapped and blindfolded etc. - would be awful enough for an adult woman, but for a young teenager excruciating.
It was definitely sexual assault and it was definitely abuse. Since you were a child, I'd say child abuse too, despite the age of the first perpetrator. I just want to validate you here - abuse is abuse, even if the abuser was your age. He must have known that what he was doing was totally wrong. You were not a couple of 4 year olds playing doctor (which might be abusive, might not). Here there is no question.
Welcome to the forum

and

for having the courage to join up here and post right away with the issue at hand.
Where to go with this? Maybe today it's just good that you posted on here and will get replies with validation and support? Then in the next couple of days I'm sure some of us on the forum including myself could give you some more suggestions. Certainly, try and find a therapist, if and when you feel up to it, but there is plenty of other information and links we can give you too.