Billy Ray Cyrus felt powerless to help his daughter Miley after she became embroiled in a bong-smoking scandal last year (10) - because he was suffering from depression and was "numb" to pain.
The teenage sensation hit the headlines in December (10) after she was filmed puffing on a huge pipe allegedly containing hallucinogenic legal high Salvia.
At the time, her dad Billy Ray took to his Twitter.com page to apologise to Miley's fans and express his disappointment, writing: "Sorry guys. I had no idea. Just saw this stuff for the first time myself. I'm so sad. There is much beyond my control right now."
The country singer has now opened up about the incident, admitting his regret for failing to provide support for the Hannah Montana star.
He tells CNN newsman Piers Morgan, "Bong-gate happened in the midst of my darkness, in my darkest hours. By then, I was a bit numb of pain at that time. And realising that, you know, oh my gosh.
"As a father, I was alarmed for my daughter's safety but at the same time my whole world was crumbling apart beneath my feet anyway so there wasn't a whole lot I could do."
But Billy Ray is full of pride now after watching Miley bounce back from the controversy by throwing herself into her career.
He adds, "I think she's well on her way to being the happiest I've ever seen her. I think she's thriving as an artist right now. She has two movies in the can that she's worked on over the past several months."