I know I shouldn't ruin this, but Matt didn't say what was in his heart, it was on script. Though I'm sure that he meant it. But, Matt did cry during the script read of that, when he said "I'll always remember when the doctor was me"
I think we really do forget though. His kids were grown by the last day of the Time War, but his grand kids were likely among the billion children on Gallifrey that day. :( <<Well, thanks for ripping my heart out and crushing it into dust.
Moffat did say they were going to play with that episode in the new season. --> awkward when if thats the twelfth doctor, where is his TARDIS? And if the tenth doctor saved him then what happened to his TARDIS in pompei?