The Russian singer - who has 12-month-old daughter Lucia with the 'Braveheart' actor - began recording the conversation in which he branded her "a ****" and a "f***ing selfish b***h" because she was convinced he might kill her and wanted evidence to prove it in the event of her death.
Oksana - who has denied being responsible for making the recordings public - said: "I started taping it around 11 o'clock because I thought I'm actually not going to live through the night. I wanted my mother to be able to prove that if I'm dead that this is who did it. "
As well as explaining why she taped the phone call from Mel, Oksana also explained some of her comments to him, admitting she thinks he needs "treatment" because his rants were those of a sober person, not someone under The Influence of alcohol.
She told Larry King in an episode of his talk show which is due to air in the US tonight (17.11.10): "There was no liquor, not once. He never drunk. I mean, one time he drunk when he was away. That's the only time he drunk.
"I've never ever seen him drinking. That's why I keep saying on those tapes, you need medication. He does need medication for the sake of our daughter. He needs to be treated."
She said: "On January 6 this year the beating took place. Mel actually assaulted me whilst I was holding the baby in my arms.
"It was at his house, our house at that point. I ran into my son's bedroom and told him to hide because Mel is crazy, he's getting really violent."
It was revealed earlier this week that in court documents, Mel confessed he had slapped Oksana, but said he only did so because she was acting hysterically while holding their daughter Lucia.