The day of the Doctor (The Day of The Doctor) (№ 387325)

He often tells of a day when did. When he killed all the Time lords to stop the war.
And I would say that.
- I would not speak. Because you haven't done so. It is still ahead of you.
- You're very confident.
- He regrets it. I see it in his eyes every day. He would have done anything to change that.
- Including saving all those people. How many worlds has his regret saved, do you think?