[He puts her on the spot, and her eyes manage to grow wider for a moment. She isn't expecting him to ask that, of all things. And she really isn't sure how to answer at first.]

We eventually make our way to Trenzalore.

[Her words are soft and carefully selected, eyes never leaving his as she speaks.]

And I did what I was born to do. I saved you, Doctor. I couldn't let my clever boy's light go out. The universe needed you. I needed you.

[She gives a shaky exhale, one side of her mouth tipping upward in a sad but accepting smile.]

So I did the impossible and I leapt into your timestream.

[And obviously it worked out just fine with hardly any lasting damage. She only tore herself apart into thousands of pieces, spread across all of time and space to find and save him. A piece of her has been everywhere with him, in exactly the right time and at exactly the right place. They go all the way back to Gallifrey, a piece of her guiding him to his specific Tardis he runs away from all those endings he never wants to face.

She's still in one piece though, and shrugs to show him that it wasn't any big deal. She had been avoiding telling him this, because he deserves to live it and experience it himself. ]