Should I tell my friend?

I think my bff bro is kinda cute and although we tell each other everything I know that if I told her this she would never let me live it down. Its a harmless crush considering hes 3 years older than me and has a girlfriend, but I have a feeling that if...

I tell her she'll tell him. What shoudl I do?

if you think she's going to tell her brother that you like him, then maybe you shouldn't tell her then...or you could just tell her in a jokingly way and she what her reaction is...but it's better to be safe so maybe you shouldn't tell her...hope I helped