"How could this happen in our marriage?" the 27-year-old wonders aloud. "Josh is my first love, he's my one and only."
"I didn't know what to do, I knew we needed help," she adds. "My only hope was to cling to my faith... If I went off of what I was feeling, I would turn a mess into a disaster."
"It was such a betrayal for a spouse to go through what we're walking through," Anna says. "It was a betrayal for those that call themselves Christian. To vow before God to be loyal to each other, and that loyalty was broken."
"Anna is planning on getting back together with Josh, that's just how it goes," the source said. "The family was taught to have a new level of forgiveness towards Josh."
On the three-part TLC special
, several members of the Duggar family have tearfully shared what Josh's multiple scandals have done to the family.
"Just thinking about what Josh has been speaking for, and how our family believes as a whole, that what makes it so unbelievable," Josh's sister, Jill, explained during last week's premiere. "It wasn't right for him to let us [defend him] without having the full knowledge of what he was hiding."
The cheating scandal hit particularly hard after Jessa Duggar revealed that the family had already spent years learning to trust 27-year-old Josh again, who, in May, admitted he had molested five minor girls as a teen, including four of his sisters.
"It was shocking. You don't expect something like that to happen. It's your older brother. Somebody you love and who you trust," she shared. "So definitely there was a period of time in our family where Josh was not to be trusted. He spent time away from home, getting help."
"Trust isn't instantly rebuilt," Jill added. "You can forgive in your heart, but at the same time it's a journey to rebuild that trust."
The second part of Jill & Jessa: Counting On airs Sunday, Dec. 20 at 8 p.m. on TLC.