My Fear Is Real

At 12 I was asked for my hand in marriage by a second cousin, and seeing as I'm middle eastern it wasn't all that bizzare. I was very close to his brother, who was like a brother to me, and my dad and him kept it a secret from me. Didn't want to worry me about something such as marriage at such a young age. 
I was 13 when I met him for the first time, the only connection to him was that he was my favorite cousin's brother. He would flirt constantly with me, and I was scared. Why is he doing this? Didn't I already say no? Why is no one helping or listening to me? It was so confusing and little by little I'd memorize the sound of his footsteps in order to avoid him since he lived in the same building. 
At 14 I'd hear his laugh from afar and flinch. I'd hear his name and walk out of the room, trying to erase him from my memory. I'd smell his cologne in the streets and feel my heart beat faster in fear. I still can't eat that certain food that I had at his house because too many memories come tumbling in without permission. 
I told everyone I could, only to not be believed. They'd all say he was just being friendly, that my fear was uncalled for. Why would I throw away the beautiful jewelry he gave me? Why would I talk to his brother so freely and not speak a word to him? All these whys that I already gave an answer to, asking for a different answer. I just want to be heard. Believed. Be told I wasn't imagining it all. Maybe some advice, please. Thank you.