letourneau and vili fualaau and their two teenage daughters spoke to barbara walters in a 20/20 interview that will air friday .
letourneau and fualaau got close as she gave him extra help with his artwork when she was his sixth-grade teacher in 1996 .
she said that she thought they would be able to stop at just a kiss but it went much further - and she fell pregnant when he was just 13 .
she served a few months in jail and fell pregnant with his second child within weeks ; she was then sent back to prison for seven years .
but a year after her release in 2004 , they married and are still together .
vili fualaau lamented that he did n't have the right support as a young father of two girls and detailed his history of depression .