From Clara discovering he had a wife to his face as he tries to pretend he can’t see her to him finally facing an ending, this was an escalating game of bittersweet that ended in the perfect goodbye.
And of course you have to talk about his reaction to not being able to respond to River when she says his name. Normally he’d call her out on it - say something - he never holds back with her, but he can’t. And his face. He’s just… hurt. No anger or frustration. Because he can’t argue with her or even just shout “RIVER!” He can’t speak to her at all. He has to pretend she’s not even there and you can see his face fall before he just shakes his head and pushes all those thoughts away.
But in the end, she got to see her Doctor again after all and he finally faced her death after all these years.