My ex boyfriend and I talk often and his best friend was talking to me in "naughty" ways when my ex and I were together. I still care about my ex, and I want to tell him what went on but I don't want to lose his best friend as one of my friends too?

It would be a difficult task to come clean about your inappropriate discussions without incriminating yourself. The first thing that comes to my mind is .. You may have encouraged this inappropriateness by enabling it. You have to accept your own part of the blame for allowing it. Had you nipped that in the bud, he wouldn't have got the impression that you are receptive .. And would have stopped.

Make no mistake .. Being disrespected  by this "friend" .. Whether or not you enabled it, is, for obvious reasons reflects very negatively on your relationship with this guy. THAT is not what a friend does to another friend .. So don't fool yourself into thinking he wants your friendship ... Cause THAT is not what he's after...if you get my meaning.