'You cry until then you can't cry, and then you cry some more,' the 53-year-old singer says in her new book The Key Is Love.
The singer describes how she coped with the devastating loss in the memoir, which she says was inspired by her mother Olive's advice.
'Some people don't talk about these things, but we do,' said Marie in an excerpt published in People magazine's latest issue. 'I think it's important. I'm healing every day.'
Devastating loss: Marie, pictured in 1999, opens up about the pain of losing her son Michael, second from left, to suicide in 2010 in her new book The Key Is Love
Candid: The 53-year-old describes in her book the moment she found out about her 18-year-old son's death as the 'worst thing' to have happened
'My sweet son left me, his family, and friends by jumping from the balcony of his eighth floor college apartment in Los Angeles,' she says of that fateful day in February, 2010.
'Even as I write this I want to cry out, "Please, don't let this be true,"' adds the star.
Marie was staying in a hotel room at the Flamingo in Las Vegas with her daughter Rachael, 'exhausted from a non-stop week with shows,' she explains.
The singer was awoken at 1:30am by a cell phone call from guard in her neighbourhood.
'He said, "Someone is here from the coroner's office. They are coming to the Flamingo to see you,"' said Marie.
She says her 'heart dropped to the floor' as she told her daughter 'It has to be Michael.'
Rachael tried calling her brother's phone but there was no answer, so she kept redialing.
'She kept saying "Pick up, Michael. Be there,"' recalls Marie.
Then came the knock on the door that every parent dreads, informing Marie that her son had committed suicide earlier that evening.
'I thought someone had run a knife into my heart,' writes the singer.
'Lousy marriage': Marie adopted Michael with her second husband Brian Blosil, pictured in 2001, who she split from in 2007
'Michael was an adventuresome child,' she recalls fondly. 'It was impossible for anyone in the family to stay upset or angry if he was around.'
When Michael was 13, a woman rang the family's doorbell and revealed herself as his birth mother.
'We all sat and talked for over an hour,' says Maria. 'Michael was intrigued and excited.'
But his biological mother disappeared after that, which Marie says 'seemed to confuse him at an age when he needed the most stability.'
The star is also candid about her son's prolonged battle with drug addiction, which started at the age of 12.
Marie blames herself and her own depression in her second marriage for his struggles, claiming that 'Michael sensed my hopelessness. It's too much pressure for a child to worry about his mother's happiness.'
Things looked up in 2009 when Michael enrolled at The Fashion Institute of Design and Merchandising.
'Michael had made a promise that if I even suspected him of doing drugs I could kick him out the house,' she recalls. 'It was something we never had to contemplate because my son made good on his promise.'
It's my fault: The star blames her own unhappiness in her marriage for her son's struggle, claiming that he 'sensed' her hopelessness
'He had no idea how he got there,' says Marie. 'He said he had not had any alcohol or taken any drugs on his own, but felt that one of the people in the car must have laced what he was drinking with something.'
Although Michael never told his mother about the incident, she says two days before he died she heard a change in his voice.
'It frightened me,' she says. 'He sounded weary and said that he felt like he had no friends.'
In retrospect, Marie says she realises her son was hiding how depressed he truly was.
She insisted that he come to Vegas to see her, but he didn't want to miss any classes.
Marie says she has replayed that final conversation 'thousands of times' in her mind.
'My one consolation is that I never end a conversation with my children without saying "I love,"' she says. 'It was the last thing I said to my son.'
Since his passing, Marie says 'not a day goes by that Michael isn't my first thought in the morning and my last before I fall asleep.'
The singer remarried her first husband Stephen Craig in May, 2011, and she says she felt Michael near her shoulder during the ceremony.
Second time around: Marie said she could 'feel' Michael's presence when she remarried her first husband Stephen Craig in May, 2011
Marie describes her son as a 'mallard,' because he looked a bit like a duck when he was a baby.
'Mallards look so serene, yet they have to paddle continuously to stay afloat,' she says. 'Give them a safe nest. Please, don't wait. Remember, depression doesn't wait until Monday.'