Friend std

My friend just called and said she has a STD. The person she had sex with recently she said she may of gave it to him. i brought them together he is one of my friends and i'm extremely scared for him as well. She said she doesn't want to tell him, but he is my friend as well. If i respect her wishes and not tell him am i wrong ?

they are both my friends. I don't want to hurt either of them but i know he needs to know.