Is it better to tell your friend or not tell them if you find a revealing pick of them online?

I was browsing drunk girl pics on a blog yesterday (What can I say.. I'm male, if I wasn't interested in that stuff I'd either be gay or dead) In the photo gallery I saw a nip slip picture of a friend of mine. My friend would neither knowingly allow a picture like this to be taken, nor allow it posted for public view online. It was obviously taken without her knowledge, and she was most likely unaware of the revealing possition of her tank top at the time.

I felt that as her friend I should tell her about the pic and send her a link to see for herself, However I am afraid it would be embarasing to hear about this from her male friend that she knows used to be crushing on her. I am probably one of the last people she would have wanted to see something like this. Damage is done as I emailed her about thislast night.. Did I do the right thing or should I have kept quiet about this?