"Stop it? Wut do you mean I can stop this? I did stop this."

After he makes that remark, it does click in his head that what he saw, probably wasn't real. Very slowly, his hearts begin to slow down a bit. The images begin to slowly fade. However, the terror on his face still remains for the moment.

He finds himself trying to figure out what is going on here. The Doctor swallows hard, "Where did that - come from?"

Why are you being so kind?