Need support

i was at a party and someone’s brother was there. he is 15. i am 18. we were all drinking and most of the night he was touching me and kissing me and i remember saying no over and over.

long story short we had sex. he said that i told him yes but i know for a fact i said no many times before it. also i yelled stop halfway through and left the room. he let me go and didn’t bother me the rest of the night.

we go to the same school now i’m finding out that he’s gone around telling everyone that we had consensual sex and that i wanted him.

also note that i can’t tell my parents because if anything i will get in trouble because of him being a minor

any tips on how to deal with this?