Washington (CNN) The women say they were treated like dogs and told that their children would be given up for adoption. They lied awake at night, wondering if their kids were safe.

But even after being reunited with their children, they say their nightmare has not ended.

Their anguish is conveyed in a collection of letters written from one of the few immigrant family detention centers in the country, where some moms and children who were separated at the border this summer are now being held together while they await their fate. The mothers' writings reflect a mix of despair, bewilderment and hope as they remain in government custody and legal limbo, weeks after they were reunited.

"My children were far from me and I didn't know if they were okay, if they were eating or sleeping. I have suffered a lot," wrote a mother identified as Elena. "ICE harmed us a lot psychologically. We can't sleep well because my little girl thinks they are going to separate us again. ... I wouldn't want this to happen to anyone."

The letters reflect the scars inflicted at the height of family separations this summer, when thousands of families were broken up at the border and kept apart for weeks to months at a time. They also reflect the ongoing uncertainty and emotional recovery for the families that are still detained.

The letters were collected at the Dilley detention center in Texas. They were provided via the Dilley Pro Bono Project by the Immigration Justice Campaign, a joint effort by leading immigrant advocacy and legal groups to provide access to legal support in immigrant detention centers.

The mothers speak with the Dilley Pro Bono staff in visitation trailers in the evenings and had expressed a desire to tell their stories to the public. The staff suggested writing them down, and the mothers agreed to write the letters, translated from Spanish, under pseudonyms.

None of the allegations of harsh treatment in the letters are specific enough to be attributed to a particular official, facility or agency. "We treat those in our custody with dignity and respect, and take all allegations seriously, and we investigate all formal complaints," a Customs and Border Protection spokesperson said, pointing to internal standards. CBP takes custody of undocumented immigrants if they are caught at the border and holds them short-term until they can be transferred to longer-term custody.

Immigration and Customs Enforcement houses immigrant adults and families in long-term detention. ICE spokeswoman Sarah Rodriguez told CNN that the agency was unable to respond to the allegations without more specific information.

Mothers describe trauma of being separated

The letters detail the mothers' vivid memories of the moments they were separated from their kids.

"They started to call children's names and also the name of my son; he was asleep on the floor," wrote a mother identified as Elba. "I woke him up and told him, 'Son, you are going, maybe for only a week.' We both cried when we said goodbye. We didn't know it was for 75 days."

"What hurts me the most is that my daughter got her period for the first time when we arrived at the icebox and I was unable to help her. It was the first time and it tormented me. She yelled to me from against the chain-linked fence that her pants were filled with blood and I was unable to help her," wrote "Isabella." Immigrants refer to temporary border facilities that are kept at low temperatures as the "icebox."

"We have suffered a lot. What the president did to us cannot be described," wrote a mother named as Camila. "What will he gain from making so many people suffer in this way? What would he do if they took his child and didn't tell him where they have him and made him a prisoner and gave him dog food like they gave us in Port Isabel jail? ... Thank God now we are together and (my daughter) is now recuperating."

"The moment when they separated me from my son I felt destroyed. I didn't know what was going to happen to my life because the officials told me that I would never see my son and that he was going to be given up for adoption," wrote "Sandra."

"For me those months were so desperate. I didn't even eat or sleep. I felt traumatized and the worst was when I looked at them and asked for my child the first thing they said was that he had been given up for adoption. I just cried and cried."

"We left our country to protect our children and to offer them a better future, not so that they would separate us from them and not for them to treat us like criminals," wrote Maria. "The mark left on each of us the mothers and children from having lived this torment is one of the saddest things in our lives. I thank God for giving me the strength, hope, and will to keep fighting for God. There is no more beautiful miracle than knowing that outside there are people who are supporting us and that we are not alone."

The CBP spokesperson said CBP "strongly disagrees" with the characterizations in the letters, saying "the alleged incidents do not equate to what we know to be common practice at our facilities." The spokesperson also said it was impossible to respond to nonspecific allegations.

The government has maintained throughout the process that immigrants are well treated in detention centers and that the separations were justified as a consequence of a decision to prosecute all adults who cross the border illegally, including parents.

But on June 20, the President signed an executive order reversing course and ordering families be held together. Less than a week later, a judge ordered the families that had been separated be reunited, barring a specific reason to keep them apart.

Living in a legal limbo

Earlier this summer, the federal judge that ordered the government put the families they separated back together also then paused any deportations of those reunited families. Lawyers representing the immigrants successfully argued that the families needed time with lawyers to weigh their options, and that the children had their own rights to seek status in the US.

Most of the families who were separated have since been reunited, save mainly for parents deemed unsafe or who were deported. And of the reunited families, the majority were released from custody, pending further immigration proceedings.

But dozens of families remain in detention centers, many with pending deportation orders. Those families are wait in a legal limbo, unsure if they will be released or deported -- all the while, still trying to recover from the trauma they describe experiencing while separated.

It's unclear how much longer they will have to wait.

The government and immigrants' lawyers are nearing an agreement that would give many of those parents a second chance to stay in the US, acknowledging the duress of separation may have impacted their ability to make their case.

"It has not been easy to be separated from my son. Now that we are together I hope that soon we will get out and this will only be a bad memory," wrote a mother identified as Anna.

"You will see that what we lived was a horror," wrote Gabriela. "I wouldn't wish it even on my worst enemy."