This is going to sound wierd, but I think you should just forget them both. The one going out with your friend..it's your friend, so yeah, he's gone. The other one, you said you went out with him before? So it obviously didn't work before..won't it not work out again?
Sorry, but thats what I think, I think you should find someone thats not with your friend, and one that you've already been with in the past.
“Some days even my lucky rocketship underpants won't help.”
-Calvin & Hobbes.