He pulls Joan into a last, tight embrace; his heart is so heavy and he can't keep the tears from gathering in his eyes. Then she pushes him away with a kind of desperation.
"Go," she says. "Do it."
He knows she will shed no tears while he is with her. He lets his gaze rest on her for one second longer, and then with a half-sob he turns and bolts out the door, with the watch clutched in his hand. Once he is out of sight of the house, he falls to his knees. The call of the watch is so strong, almost forcing him to open it.
"I hate you," he whispers. "How dare you destroy my life this way?"
You are me. Open me. Set me free. Save this village. This country. This world.
The weight of the world on his shoulders. How can the Doctor stand it day after day for hundreds of years? Never a reward, hardly ever a thank you.
"For two months I was completely happy," he says. There is an impulse in him to fling the watch as far away as he can. "What if I don't open you? What if I go and fight them myself, without you?"
You can't. They're not human. They can die, but can't be killed. Open me quickly; time is running out.
He drops the watch to the ground and looks at it in the dim light. The sound of destruction in the village resumes, and his heart almost fails him. Well, he is doing the right thing. No one but Joan and Timothy will ever know, but he is doing the right thing, and that's all that counts. Soon, he will cease to exist. But Joan. Oh, Joan! She will be alone. Again. She might live out the rest of her days as a widow, ignored by the world, always tending to the hurts and illnesses of young boys while slowly fading away. She has no children of her own, no family that he knows of. She will be forgotten, as he will be, but it will be worse for her.
Another explosion shakes the ground and he looks up.
"All right." He growls and picks the watch up. "But before I go, Doctor, I want to say this: you like to show mercy when you can, and that's good. But this time, for Joan's sake, for my sake, don't show the Family any mercy. They've destroyed too much and too many. Their lives are more worthless than my own."
He looks back towards the house that he cannot see and murmurs, "Goodbye, Joan dearest." And he opens the watch.