"Last year, after Bristol and I broke up, I was unhappy and a little angry,” Johnston tells People, referring to the mother of his son Tripp. “Unfortunately, against my better judgment, I publicly said things about the Palins that were not completely true.”
The 20-year-old ex-high school hockey hero does not spell out which accusations were lies.
Following his split with Bristol Palin three months after Tripp’s Dec. 2008 birth, Johnston lashed out at Sarah Palin, accusing her of badmouthing her job as Alaska governor in private and alleging that she and Todd Palin were on the path to divorce.
He went on to pose for Playgirl magazine and threatened to go public with more dirt that "could hurt" the grandmother of his child.
In response, Palin termed Johnston's taunts "mean spirited, malicious and untrue" and criticized his Playgirl decision.
Johnston said he’s apologized to Todd and Sarah Palin privately for what he termed “my youthful indiscretion.” But he told People he owed the family a special mea culpa in the media “since my statements were public.”
"I hope one day to restore your trust," he said.
Johnston has already earned kudos from Bristol Palin -- if not the rest of the Palin clan -- for coming forward.
On Tuesday, the former teen mom told People: “Part of co-parenting is creating healthy and honest relationships between the parents. Tripp one day needs to know the truth and needs to know that even if a mistake is made the honorable thing to do is to own up to it."
Last month, Johnston’s manager revealed that after a nasty custody fight the ex-couple had been spending more time together for the sake of their son, but denied they were again dating.