To be a mother

What if your only chance to be a mother was to give birth to his first wife's child? All I've ever wanted is to be a mother. And since I married David, it's gone from being a dream of mine, to a dream of ours. And I want it for him too. It's the happy-ever-after he deserves after the tragic loss of his first wife, Katherine. We have tried and we've hoped. But today I've just found out it's impossible. That I'm unable to become a mother. My heart...