I'm trying to find a fic where Dean is captured by Meg (or maybe it was Ruby?) and Meg blackmails Sam into becoming a part of her big plan. But Sam refuses so Meg calls in her human goons and tells them to rape him, which they do and video tape so the tape can be sent to Sam (to forcefully persuade him to join her side or else more damage will be done to Dean.) In the end Dean is saved by Sam however.

I think it continued around the middle of Season 4, just before Lucifer Rising.

Any help is appreciated, thank you very much in advance!

EDIT: Found it, it's called Blinded in Trust! (Thank you, )