Edwards' Ex-Mistress' Sister Pans Both

The family of John Edwards' "other woman" is "very upset" with both Edwards and his former mistress, Rielle Hunter, Hunter's sister says.

In an exclusive interview with "ET," Roxanne Druck Marshall told ET's Thea Andrews her heart goes out to Edwards' wife, Elizabeth, who has advanced breast cancer.

Marshall says, if she could, she would tell Elizabeth, "I'm sorry. I'm so sorry for what my sister did and what her husband did, too. I mean, they both did it together. You don't make a baby with one person, and it's horrible. I mean, what she must be thinking, and feeling. I just... my heart goes out to her."

It should be noted that Edwards denies fathering Hunter's baby.

Andrews says Marshall described her family as hurt and embarrassed by what happened.

And, during a preview of the ET story, Andrews remarked to Early Show co-anchor Harry Smith, "Roxanne tells me she believes John Edwards has her sister hidden away somewhere, so the press won't be able to find her."

Andrews added, "Roxanne says John Edwards has been untruthful in many of his statements to the media about the affair. She says that, contrary to what John Edwards says, the affair with her sister started long before she started working on the campaign, and that it never really ended; that they are still in contact today, that they've spoken recently, and that her sister is still very much in love with John Edwards."

To see the entire Early Show preview of the ET interview, click on the arrow in the image below: