The Crown saison 3 Episode 10
The Queen: "For the record, I think there are many things you're good at.
Princess Margaret : "Name one that's actually meaningful."
The Queen: "Being a sister."
Princess Margaret : "No need to humor me."
The Queen : "I'm not. Of all the people everywhere, you are the closest and most important to me. And If by doing this, you wanted to let me imagine for one minute what life would be like without you... you succeeded. It would be unbearable."
Princess Margaret : "Then we must both carry on."