mixedmedia

I think you should tell her...in an accepting and reassuring way.

"Look, I know this sounds bad because I am admitting that I look at porn on the internet, but I came across this picture..."

Let her know that you don't judge her and are only saying something because you want her know if the picture isn't up there with her consent. Tell her, tell her where you saw it and leave it at that. Don't press her about it.

I'm not sure what sort of significance sex has in communicating with your family. If it's a subject that is a no-no to talk about, then it may make talking to her more difficult and may give you reasonable excuse for not mentioning it. But if it were me, I'd want my brother to tell me. Your mileage may vary.

I love your avatar by the way, BCD...I saw the real one in Houston a few years ago. It was overwhelming to stand and view it from the same distance he stood to paint it.

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Most people go through life dreading they'll have a traumatic experience. Freaks were born with their trauma. They've already passed their test in life. They're aristocrats. - Diane Arbus
PESSIMISM, n. A philosophy forced upon the convictions of the observer by the disheartening prevalence of the optimist with his scarecrow hope and his unsightly smile. - Ambrose Bierce