.. im really scared?

i juz got out of skool and im really scared. this guy at my skool kept flirting wth me and i wantd him to stop. aftr skool wen i was walkin he took me to the corner pulled my pants down and d me. so i got grip of him and pulled him away and ran off to find my bf. i went home crying wthout telling my chilhood sweetheart wut happend. he and i hav been goin out for nearly 6 years and we promised eachothr no and take things slow. how do i tell him? i kno he wont get mad at me cuz hes so sweet. but shuld i tell him about this guy?