Melania Trump describes in her new memoir how she made her husband, then president Donald Trump, drop a signature hardline immigration policy under which migrant children were separated from their parents, stoking domestic and international uproar.

“This has to stop,” the former first lady says she told her husband, “emphasizing the trauma it was causing these families” and seeing him swiftly comply, ending the policy on 20 June 2018.

It is not the only spousal disagreement revealed in the memoir, Melania, which will be published in the US next week. The Guardian obtained a copy.

Melania Trump also delivers a passionate defence of abortion rights significantly weakened by a supreme court to which her husband appointed three hardline justices and under further attack as he runs for the White House again.

Like abortion and reproductive rights, immigration is a hot-button issue in the campaign that will culminate on 5 November when Americans choose Trump or Kamala Harris, the Democratic nominee, as president for the next four years.

“Occasional political disagreements between me and my husband were a part of our relationship,” Melania Trump writes, “but I believed in addressing them privately rather than publicly challenging him. I found our discussions more productive when we could have a quiet dialogue at home, out of the public eye.”

She writes of her immigration concerns: “Given my past experiences with unfair media narratives, I always approached the news with some skepticism. Before discussing the border crisis with him, I thoroughly educated myself on the situation.”

Reports of children “being held in overcrowded detention centers and in absolute squalor … raised serious questions about their health and well-being. The lack of a clear plan for reuniting families and the absence of a definitive policy on these separations only added to the public’s outrage. I felt strongly that the situation demanded urgent attention and action.”

Describing approaching a husband “whose hardline stance on immigration was well known”, Trump writes: “I am sympathetic to all who wish to find a better life in this country. As an immigrant myself, I intimately understand the necessary if arduous process of legally becoming an American.”

Born in Slovenia, Trump became a US citizen in July 2006, eight years after meeting Donald Trump and shortly after giving birth to their son, Barron. That same month, Donald Trump had the sexual encounter with the adult film star Stormy Daniels from which arose his 34 felony convictions regarding hush-money payments.

Melania does not address that scandal in her book. Regarding child separations, she continues: “While I support strong borders, what was going on at the border was simply unacceptable. I immediately addressed my deep concerns with Donald regarding the family separations, emphasizing the trauma it was causing these families. As a mother myself, I stressed: ‘The government should not be taking children away from their parents.’ I communicated with great clarity … ‘This has to stop.’

“Donald assured me that he would investigate the issue, and on 20 June, he announced the end of the family separation policy.”

The first lady’s intervention was reported at the time. Also widely reported was an incident that occurred when she visited the southern border herself.

A first visit made her think “the root cause” of family separations “was not the government but rather the dangerous influence of criminal cartels in their home countries”.

But when she made a second trip to meet desperate migrant children, she stirred controversy by travelling in a jacket emblazoned with a slogan, “I really don’t care, do U?” that many thought insensitive at best and callous at worst.

On the page, Trump says the message, which she calls “discreet yet impactful”, was meant as a protest against anonymously sourced reporting.

“I was determined … not to let the media’s false narratives affect my mission to help the children and families at the border,” she writes. “In fact, I decided to let them know that their criticism would never stop me from doing what I feel is right. To make the point, I wore a particular jacket as I boarded the plane, a jacket that quickly became famous.

“As the door on the plane closed, my press secretary’s inbox was flooded with urgent emails from top-tier media outlets regarding the jacket … ‘It’s a message for the media,’ I said, ‘to let them know I was unconcerned with their opinions of me’ [but] she told me I couldn’t say that. ‘Why not? It is the truth.’ I disagreed with her insistence that I couldn’t say that. Ignoring my comments, she told a CNN reporter she was friendly with that it was simply a jacket, a fashion choice with no underlying message.”

Trump says the subsequent fuss “overshadowed the importance of the children, the border, and the policy change” and was “just another example of the media’s irresponsible behavior”.

But the press secretary she blames for communicating “misinformation” about the jacket, Stephanie Grisham, wrote in her own book that when the two women got back to Washington DC, they were told off by the president. Contradicting Melania’s claim to have worn the jacket to target the media, Grisham says Donald Trump came up with the idea, shouting: “You just tell them you were talking to the fucking press.”

Recent reporting suggests a different motive on Melania’s behalf. According to Katie Rogers, a New York Times reporter, the episode was part of a four-year “internal power struggle” between Melania Trump and Ivanka Trump, Donald Trump’s daughter and senior adviser.

As described by Rogers, Melania and Ivanka were “locked in a quiet competition for press coverage”, prompting the first lady to scrutinize every “mention of her name in the press … often trawl[ing] Twitter to see what the press, her critics, and her supporters were saying about her” – and then to seek ways of boosting such coverage.