Lisa Marie Presley's divorce is about to get even nastier.

After the star accused estranged husband Michael Lockwood of collecting "hundred of inappropriate photos" of children, the bitter musician claimed in legal documents last week to have his own dirt on the late Elvis' daughter.

And now, Breaking Celebrity News can exclusively reveal some of the damning details that could separate Presley, 49, from her young children forever.

"Michael took pictures of Lisa Marie when she was naked and out of it," a family insider tells Breaking Celebrity News.

During the last days of their marriage, "they both walked around the house naked a lot," the source added. "They even skinny dipped with the kids around."

Presley, who checked into a California treatment facility for an addiction to alcohol and drugs last summer, was "on pills and sleeping all the time" before her split from Lockwood, the source added.

As Breaking Celebrity News readers know, Presley and Lockwood's 8-year-old twins Finley and Harper are currently in state custody. (Presley's mother Priscilla claims to be caring for the girls.)

Now, Presley is terrified Lockwood's potential allegations could tear her away from her daughters for good.

"It's leverage that Michael can hold over her head," the source said. "This could well impact what happens to the twins, and she is very frightened."