I've been there. Heaven. You came for me, you knew where to look.

[ Jack already mentioned that he was dying so that was just the next step on that road. He isn't going to talk about how Castiel gave up his future for Jack. He wouldn't understand that now, since he isn't his father. Jack liked Heaven, and the Garden, but he knows that the Empty is all he can expect now. ]

But your relationship with the angels now, it's very bad, Castiel. You told me I shouldn't trust them, and you were right.

[ They tried to kill him and then they used him when he was soulless. His power was exactly what they needed. Jack doesn't blame them for his actions, it was still his choice to do as they asked, but he knows not to trust them again. ]

How did you meet my fathers ... the Winchesters, I mean.