My Sexual Assualt Story (possibly triggering to some)

I was in seventh grade and my family went on a trip to Maui for spring break. There was a very large pool at the resort and it had the worlds only underwater elevator, so obviously I went on it a lot. I met this one guy who was either 16 or 17, I don't remember exactly, and we started talking (I looked about 14 or 15 at the time, I was 12). After a day or so I began to get freaked out because he was just really clingy and he wouldn't leave me alone, I have pretty bad anxiety so I didn't tell him to leave, instead, I ran away from him whenever I had the chance. One day, later in the night, the pool was clearing out and I decided to go the elevator one last time, he was there too. When we went up nothing really happened, he grabbed my thigh, which kind of freaked me out, but that was about it. When we got to the top we went to go choose what waterslide to go down except he grabbed me and pulled me to the side, I could tell he was annoyed, but not neccessarily angry. I froze as he began to touch me everywhere. He grabbed my boobs pulled me by them while I was frozen in place. He put his fingers inside of me, but didn't rape me, and I am forever grateful he didn't. I couldn't move or think or breathe. The only thing I vividly remember was how his fingers curled inside of me and the panic that came along with it. I still don't know if he took my silence as a yes, or if he even cared if I wanted it or not. When he was finshed he acted like everything was fine. He didn't even tell me not to tell anyone, he was almost proud of what he had done to me, or maybe he thought he did nothing wrong. After that I walked back to my hotel room in shame and fear. I can't help but think that if I had screamed or moved away he would have stopped. I still have flashbaks and I no longer enjoy hugs or intimacy. Does anyone know how I can help this? It's almost been four years and recently I've been suffering from sleep deprivation because I can't stop thinking about this. I know so so many people have it way worse than me, but any tips on managing this would help.