Omg Help Me Please !!!!?

Ook so my mom stopped smoking for a long long time. it has been like a year. So this morning she went outside and i looked to see what she was doing and she was smoking !! I am so shocked and so upset. I don't know what to do know that i know that she still smokes. I am not sure if i should tell anyone b.c then she might get mad at me. WHAT SHOULD I DO ???? PLEASE HELP ME !!!