All Estela Juarez wanted for her ninth birthday was for her family to be allowed to stay together.

The gift from Donald Trump’s administration, however, was fully in keeping with its zero-tolerance stance on immigration. On Friday, Juarez, an American citizen, will leave the only country she has ever known and board a plane to Mexico as US officials enforce a deportation order against her mother, Alejandra.

Her father, a former US marine, national guardsman and decorated combat veteran, will stay in Florida with Juarez’s 16-year-old sister, Pamela.

The breaking apart of American military families marks a new low point in Trump’s war on immigration, some White House critics believe, while Alejandra Juarez – who is being expelled 20 years after she entered the US illegally from Mexico as a teenager – says it is a “slap in the face”.

Before, if you had citizen kids or an American husband you wouldn’t be deported, but now they don’t care Alejandra Juarez

“When I think about the service my husband has given this country it just breaks my heart,” she said.

“They try and punish me for something that happened a long time ago, but they’re not punishing me, they’re punishing my husband, my kids. It makes you think if it’s really worth fighting for this country when it comes down to this, putting your life at risk for a country that doesn’t take your service into consideration.”

Juarez, 39, and her 41-year-old husband, Cuauhtemoc – known as Temo – were both born in Mexico. But while he came to the US legally as a child and became a naturalised citizen in 2002, shortly before a 16-month deployment in Iraq, Alejandra has spent their entire 18-year marriage as an undocumented immigrant.

Even so, until Trump took office in 2017, she was not at risk of deportation. “For the last four years I have been told that I wasn’t a priority, I have no criminal record, I’m a military spouse, I’m untouchable, don’t worry, you’re fine,” she said, recalling her twice-yearly check-ins with Immigration and Customs Enforcement (Ice) since a 2013 traffic stop flagged her as illegal.

“However, when this administration took over things changed. Obama didn’t fix this situation but he didn’t deport people like me. Immigration knew I was here and said under the Obama rules I wasn’t a priority. Now this administration is deporting people with no criminal record. Before, if you had citizen kids or an American husband you wouldn’t be deported, but now they don’t care.

“You see Trump on TV. ‘I love the military,’ he says – he brags about how much. But there are 11,000 military spouses like me. It has to do with this government not caring.”

On Wednesday, the family learned that Juarez’s latest and final application for a so-called “parole in place”, a discretionary deferment of removal proceedings against certain close relatives of serving or past military personnel, was rejected. Essentially, she was barred from the programme anyway because of a document she signed in 1998, when she was first caught in the US and deported. She said it was explained to her at the time as paperwork keeping her out of jail but learned only later it was a promise never to return.

The Juarez family. Alejandra said: ‘I don’t know where we will go. They might as well deport me to China or England.’ Photograph: Richard Luscombe/The Guardian

Their only other hope had been a political fix in Washington, but despite some bipartisan support, the Protect Patriot Spouses Act sponsored by Darren Soto, a Florida Democratic congressman who represents the Juarez family’s home town of Davenport, has so far failed to win enough backing to progress.

“No military spouse should be deported. It sends the wrong message to our troops who have sacrificed everything,” the politician told reporters when he unveiled the bill in April.

Soto also made no progress with a private bill for legal residence he introduced on Juarez’s behalf. “I will continue to support the Juarez family and continue the fight against the Trump administration’s heartless immigration policies tearing families apart,” he said in a statement after an expedited order of removal was issued last week.

For Juarez and her daughters, Thursday night will be spent on the sofa watching movies for the last time together as a family and trying not to think of their imminent separation. Estela, who just weeks ago was finishing third grade and planning a summer of fun with her friends, must start at school anew in an unfamiliar country and in a language she does not speak fluently.

Meanwhile Pamela, who was willing to give up her own studies to look after her little sister, whom she calls “the best thing that ever happened to me”, will have to face the challenges of her teenage years without the guidance and support of her mother’s presence.

“They’re still trying to digest it,” Juarez said. “Estela wants to stay here but is too young to take care of herself, she needs her mom. Pamela is very kind and wants to take care of her but she’s 16 years old. She is a teenager, she has a future here, she’s taking college classes, and wouldn’t have that in Mexico. Even though it’s hurting me and it’s burning me alive, I have to think about what’s best for her.

“As for me, I can’t imagine waking up in Mexico thinking where’s the last 20 years of my life? Where’s my husband? Where’s my child? It’s heartbreaking.”

No military spouse should be deported. It sends the wrong message to our troops who have sacrificed everything Rep Darren Soto

The family have no relatives in Mexico to turn to for support, and Alejandra is insistent she will not return to the same crime-ridden areas of Mexico City she escaped two decades ago. “I didn’t think it could get any worse than when I was living there but it has,” she said. “I don’t know where we will go. They might as well deport me to China or England.”

She also wonders if her marriage, which remained strong through the stresses of her husband’s various deployments, can survive this separation, especially because Temo voted for Trump in 2016.

“I said Trump was insulting Mexicans in general but he said he just talks a lot. Then when Trump released his executive orders I was mad at him. He just said he never thought it would come to this,” she said.

Meanwhile, bad publicity for the Trump administration over military deportations is becoming more prevalent. As well as American Families United suggesting almost 12,000 servicemen and women have relatives facing deportation, figures from US Citizenship and Immigration Services appear to show a significant recent increase in refusals of parole in place applications. The military news website Stars and Stripes reported this week that denials leapt from 11% in the last full year of the Obama presidency to 16% in the first eight months in the 2018 fiscal year.

In April, defense secretary James Mattis announced he planned to look into the issue but the White House has been silent since. Meanwhile an inquiry by the Guardian to Ice on Wednesday about the Juarez case did not receive a response.

Chelsea Nowel, an attorney with the Tampa immigration law firm Maney Gordon Zeller, which represents the family, said it was “incredibly frustrating” that parole in place and stay of removal applications were denied on the same day.

“She has been under an order of supervision, contributing to society and raising her family for five years,” she said. “Now, due to the new zero-tolerance policy, Ice can no longer exercise their discretion and permit her to stay with her US citizen husband and children. This policy has proved to be devastating.”