Over the course of the day, Donald Trump responded with a mix of disdain and churlishness to the parents of fallen Muslim soldier Humayun Khan. Trump suggested that as an observant Muslim Khan’s mother, Ghazala, may not have been allowed to speak and insisted that he too had made sacrifices for the country. ABCNews contacted the Khans again for an interview in which Khan’s father, livid, responded to Trump. Khizr Khan asked Trump’s children to “tell him to learn to behave, learn to be decent.”

Khizr Khan continued: “Running for president is not an entitlement to disrespect Gold Star families and [a] Gold Star mother not realizing her pain. Shame on him! Shame on his family! He is not worthy of our comments. He has no decency. He is void of decency, he has a dark heart.”

Ghazala Khan said: “Sacrifice — I don’t think he knows the meaning of sacrifice, the meaning of the word. Because when I was standing there, all America felt my pain. Without saying a single word. Everybody felt that pain.”

I confess I struggle with the emerging back and forth between Trump and the Khans. It’s good for the country because it shows what Khizr Khan aptly labels Trump’s “dark heart.” But I have no doubt that notwithstanding the well-wishes of so may the Khans will now be vilified, scrutinized and smeared by Trump’s supporters.

I take it they knew this going in and are willing to endure it as a way of honoring their son and serving their country.