AceShowbiz - Marie Osmond has spoken out for the first time since her adopted son's suicide in February, revealing the tragedy was the "hardest thing" she has ever had to deal with. In an emotional interview with U.S. talk show host Oprah Winfrey, Osmond admits she endured every parent's worst nightmare when 18-year-old Michael Bryan jumped to his death from the balcony of his Los Angeles apartment.

Recalling the last phone conversation she had with him, she says, "(He told me) 'I have no friends.' It brought back when I went through (post-partum) depression because you really feel so alone. I'm not a depressed person, but I understand that place, that darkness."

"I said, 'Mike, I'm gonna be there Monday and it's gonna be OK.' But depression doesn't wait 'til Monday." The grief-stricken singer revealed she is now plagued by feelings of regret and wonders if she could have done more to help the depressed teen.

She adds, "I think there's always 'What ifs? What if I had just put him on a plane and said come be with me, or gone there?' (But) I think if you live in 'what ifs,' you stop living." The star also defended her decision to return to the stage for her Las Vegas show just one day after Michael's funeral.

She explains, "It was really hard. It was a calculated decision. I'm unique, I guess. I'm a female in the entertainment business who has been working 48 years consistently. My stage is my safe place. It doesn't scare me, like I guess it scares some people. And I knew that if I didn't get back on stage that I may never get back on stage."

Osmond's interview will air in the U.S. on Thursday, November 11.