How about don't tell her about you can't keep seeing her as just a friend?
If you don't want to see her again until she is single and avaiable then it's easy, just avoid her in a natural way.
If you wan't to steal her from your friend and get more of the negative feelings with yourself then go search around, Im sure you will find enough about speed seduction, player and pimp related stuff.
More experienced DJs probably know of other options though.