Dean would never joke about this. Ever. He knew how people, hunters especially, would take such things. He cleared his throat, keeping his back turned to Jo as if it was something that would either make or break him if he actually admitted to the truth. Truly, he wanted to tell her the truth. About everything. The older hunter turned to Jo, pulling away from her for the time being.
This was the rift he was creating with everyone. The stoic expression on his face should be a hint enough that whatever had happened had changed him far beyond repair. At least to him it; it had changed him far beyond repair. "It burnt down, Jo. Ash, some other hunters along with it." He frowned a tiny bit, running his fingers through his hair. Before explaining everything for the most part before coming to the...'Sammy' part of that complicated mess. He really couldn't get the words 'I've got four months to live because I made a deal' out. Really he couldn't.
He glanced down for a moment before glancing up into her eyes. "Jo...I made a deal to bring him back. I needed my baby brother, it was the only way I knew how." He'd explained everything the 'war', killing Azazel. But this just seemed to be the cherry on top of the perverbial sundae. "I have four months left before I get hunted down and get dragged to hell." Kicking and screaming prefferably.