Transcript for Donald Trump's first wife Ivana Trump says she has direct number to White House

This is Amy robach. Reporter: Ivana trump is the original Mrs. Donald Trump. Once half of New York City's flashiest '80s power couple now mother to president trump's oldest children, don Jr., ivanka and Eric. At any point when you were married, did you ever think this man could be president one day? Yes. You should run for president. And I think he could do it. If there would not be a scandal. Reporter: The scandal she's referring to is trump's affair with model marl ra maples. Every American woman hated him. There was no way he could run during the scandal. Reporter: The relationship ended the marriage and made Ivana trump the ultimate member of the first wives club. And remember. What? Don't get mad. Get everything. Reporter: Ivana writes about the fallout the divorce had on her family, in the new memoir "Raising trump." Did you ask president trump's permission before writing this book? No, I did not. Because this is my life. He told her divorce is a business deal and he cannot lose. He has to win. So he took about two years, and after the situation was straightened out, we are friends. Reporter: How often do you two talk? Talk about once every 14 days. I have direct number to white house. But I don't really want to call him there because Melania is there and I don't want to cause any kind of jealousy or something like that. Because I'm basically first trump wife, okay? I'm first lady, okay? Reporter: In response to these comments, a spokesperson for Melania trump told ABC news today, Mrs. Trump is honored by her role as the first lady of the United States. She plans to use her title and role to help children, not sell books. There is clearly no substance to this statement from an ex. Unfortunately, only attention seeking and self-serving noise. What's your relationship like with Melania? Melania, it's perfectly fine. Melania is Melania. She's quiet, she lives her life. For her to be in Washington is terrible. Better her than me. I would hate Washington. Would I straighten up the white house in 14 days? Absolutely. Can I give a speech for 45 minutes without teleprompter? Absolutely. Can I read a contract? Can I negotiate? Can I entertain? Absolutely. But I would not really like to be there. Reporter: She values her treem so much she turned down an offer to be ambassador to the Czech Republic. If you want to take the position, I'll give it to you. I said I would not have the freedom. Bye-bye to Miami in the winter, bye-bye to spring and fall. Bye-bye to saint-tropez. Reporter: She goes back to the early days of her marriage when her children were young. When don Jr. Was born you decided to name him Donald Jr. What did your Donald say at that point? No, no, no, no, you cannot name oim Donald Trump Jr. I said why not? He said, what if he's a loser. Reporter: He's talking about his newborn son. I carry my kid for nine months and this is what's going to be. And the same with ivanka. He wanted to call ivanka Tiffany. Because we got trump tower from Tiffany. I said over my bed body will she be called Tiffany. She'll be named Ivanka Trump. Reporter: What kind of mother were you? I was strict but very loving. Reporter: You write full credit for raising the kids goes to me. Full credit? Donald was on the telephone making deals. He was a good provider, but he was not the father who would take a stroller and go to central park. It was only until they were about 18ears old. He could communicate with them. Because he could start to talk business with them. Reporter: The family was shattered in 1989 when trump's affair with Marla maples became national news splashed across the tabloids. Marla maples? I don't want to talk about her. Reporter: You don't even refer to her by name in your book. You just call her -- Show girl. Reporter: She found out about the affair on a family ski trip in aspen when maples came up to her and declared, I'm Marla, and I love your husband. Do you? There are reports that last year Marla maples wanted to make amends with you. Has she ever reached out to you. She asked if I would accept her apology. I said apology is never accepted. She ruined my family and my marriage. She never achieved anything her entire life. I just call her the show girl. That's all. Reporter: Why accept Donald's apology and not hers? Because it was father of my three children. And he continued to be a good father. Reporter: Ivana says her relationship with her ex-husband is mended enough that she now gives him political advice. Sometimes I tell him to just not to speak that much. And to the tweets are the tweets. I don't disagree with him. Because there's so much press against him. So if you say something, his words are going to be twisted immediately. If he tweet, then he can tell it in his own words. Reporter: She's also given support through controversies like that leaked "Access Hollywood" tape. Not really. He was not really disrespectful. He just jokes. Sometimes he says things which are serious -- Reporter: Joking about grabbing women. I don't know. That doesn't sound like anything to joke about. Okay, well, that was one instance. I don't want to go into it. Reporter: Did you ever talk to him about it? Not really, no. Reporter: One issue she's spoken about is her son don jr.'s meeting with a Russian lawyer during the campaign. Has he talked to you at all about that? I know he was not involved in any wrongdoing. Reporter: Do you worry at all about don Jr. And this Mueller investigation? Any concerns? I have zero concerns because I know he didn't do anything at all. Reporter: As Ivana seeing it having a trump in the white house could go beyond the current office. You don't want to be first wife, first mother. Reporter: And first trump wife, right? Amy robach, in New York. 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This transcript has been automatically generated and may not be 100% accurate.