Dean put his hand over hers, trying to draw her attention away from the tape. Clearly someone had touched her even if it hadn't been Lilith, and he wanted her to give it a chance to heal.
When she brought up hell he froze, just sitting there holding his hand over hers. How much of this was he supposed to tell her? What was he going to do? What he did remember was bad enough to seriously taint her view of him, and the things that he hazily remembered--well that was bad enough to make her hate him forever, he was certain of it.
"Well...for starters, I remember that the time was different down there than it was here. Sam said that I had only been gone four months, but down there, I think it was more like years and years." He paused, looking at her to see what she wanted to hear, if that was enough to settle her fears or if she wanted more. It had been literal hell, and it wasn't something he was proud of.