Sulu was finding it hard to come up with the right things to say in this situation. He had no idea how to respond to any of this, not verbally, and so he was thankful that Ianto kept talking, giving him more to respond to that could actually help, rather than apologizing and telling him he didn't hate him. He could never hate him, and that was a little scary to realize.

"It's okay. I told you, I understand why you did it. I'm not disappointed in you. Maybe, if I had been there as it happened - maybe things would be different, but after everything we've gone through, Ianto, I'm not going to hold it against you." He paused briefly, though he continued brushing through Ianto's hair, "But... maybe you should talk to McCoy about the nightmares. It might be a side-effect of whatever he's got you on."