Tonight on 20/20 we’re going to hear The Nikki Araguz Story. She’s the transgender widow of a fallen fireman, Thomas Araguz, who now finds herself battling against Thomas’ ex-wife Heather Delgado and his family for control of his estate and death benefits. The marriage is invalid, claims the ex, because Nikki was born a man — and supposedly tricked Thomas into marrying her. Bull, says Nikki. But also part of tonight’s story: How Nikki, born Justin Grahm Purdue, grew up knowing she wasn’t supposed to be a boy.