In a new clip from the TLC's three-part special Jill & Jessa: Counting On, premiering on December 13, John-David Duggar and Joseph Duggar speak out about the scandals surrounding their older brother Josh.Josh Duggar admitted to molesting several young girls as a teen, including his sisters Jessa and Jill, earlier this year. Then, Duggar was revealed to have accounts on Ashley Madison when the site's data was hacked. He later admitted to being unfaithful to this wife, Anna Duggar, and to having a pornography addiction. Anna Duggar was finally seen speaking out about her husband's infidelity in a promo for the TLC special released this week. In it, she recalls thinking, "This can't be true," when the news about Josh Duggar was revealed.In a new teaser for the series, Joseph Duggar, 20, and John-David Duggar, 25, say it was heartbreaking to learn about the actions of their brother Josh, who had been a role model to them when they were growing up."I always wanted to be like him. But one of the toughest things I ever had to tell my older brother was, 'I don't want to be like you anymore,'" John-David Duggar says in the clip, posted exclusively on People . "I've got a whole bunch of younger siblings looking up to me, and I've got to be an example to them... Because whatever I am, that's what they want to be. I know that's what it was for me and Josh."In the new promo, Joseph Duggar adds that it was a shock that Josh Duggar "was living such a secret life" of which his family was unaware. "Whenever somebody you respect the most is willing to get up and proclaim what we believe as Christians, about being true to your wife, you'd never think that that's the person who's involved in it," Joseph Duggar says in the clip. "It broke my heart."Watch the the new promo over at People