I seriously need help this is important im not playing....T-T

Me&my frend hav this guy that we rly think is awsum.we tried to be frends with him.He turned out to be a cool guy..kinda depressing but rly nice..&we were hangin out wit him..but we noticed he was frequently absent from skool
Then my frend told me the sad truth
he was using drugs.she wasnt suposed to tel me..but she did anyways..so now i cant tell any1..We dont no wat to do&we're worried
i rly need help
thx&for all u ppl out there
Stay above the influence plz..
T-T