(CNN) Seven months after an off-duty Dallas police officer shot Allison Jean's son, Botham , dead in his apartment, her attorney called with a warning: the 911 call capturing Botham's last moments was going to be played on the evening news.

Jean was on a business trip in Washington, DC, alone in her hotel room. She didn't want to have nightmares, so she waited until the next morning to listen to the recording online.

The white officer who shot Botham , Amber Guyger, told authorities 19 times during the call that she believed she was entering her own apartment, which was one floor below, and that the 26-year-old unarmed black man was an intruder. Guyger said she started giving first aid after calling police, an affidavit said.

As Jean listened to the 911 call in an empty conference room, she felt an anger that surprised her. She said she couldn't hear anyone helping Botham as he lay dying in his own home. "He was really treated like an animal," Jean said. In that moment in April, she realized she wasn't ready for the murder trial.

Ever since then, Allison Jean has been preparing herself to face her son's killer. That day will come this week, with opening statements and testimony

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Guyger has pleaded not guilty to murder ; her attorney has called the shooting "a terrible tragedy that resulted from a true mistake." If convicted, the fired officer faces up to life in prison. Her attorney has declined further comment, citing a gag order.

To prepare for the trial, Jean, 52, has attended therapy in St. Lucia where she lives and where Botham grew up. She has turned to prayer and fasting to strengthen her spiritually. Her therapist and attorney have tried to walk her through what to expect during the trial, and ways she can cope if it gets overwhelming. Her experience provides a window into what families of crime victims go through as they face those accused of killing their loved ones.

"My hope for the trial is for my son to get justice ... that the person who inflicted harm on him gets punished for the crime that she committed," Jean said.

Painful to say Botham's name

Botham liked to call his mother "GG" -- short for Governor General, the title given to Queen Elizabeth II's representative in Commonwealth countries. He was always telling his mother to look on the bright side of life, and she said his positive attitude encouraged her.

An accountant at PricewaterhouseCoopers, Botham would always take care to dress well, and encouraged her to do the same, she remembered. "You know you have to look the part," he would say.

He was her middle child, full of energy like the English cricket player he was named after, Sir Ian Botham. Jean gave him a middle name from the Bible -- Shem, who was one of Noah's sons -- and Botham grew up to be a man of faith. He grew up in the Church of Christ, led worship services at Harding University in Searcy, Arkansas, which he graduated from in 2016, and sang with the Good News Singers, a spiritual a capella group on campus. He was dedicated to charity work, and after his death, his family established a foundation to support community organizations he cared about.

Botham Jean's pastor, Sammie Berry of Dallas West Church of Christ, wears a button supporting "Justice for Botham."

On the night Botham was killed last September, Jean was visiting her daughter, Allisa Findley, 37, in New York. A social worker at Baylor University Medical Center in Dallas called Findley to say that Botham had been shot through the heart and died. She woke up her mother, trembling.

Jean sobbed in disbelief. She had just said a prayer for the protection of her three children. How could Botham be dead?

She flew to Dallas. For days after the shooting, she couldn't eat a full meal. "I was having grapes, morning, noon and night," said Jean.

She would forget to brush her teeth. She left her iPad at an airport. She felt like she was losing her memory. She saw a therapist before she left Dallas, then found another in St. Lucia after returning home.

Jean realized she didn't want to confront Botham's death, so much that she could barely bring herself to use certain words. "It was difficult for me to say words like 'die' and 'death' and 'kill' and 'murder,'" she said.

She couldn't bring herself to say Botham's name on some days. And Guyger's name, either.

"That was, for me, the most difficult part ... having to say his name, say her name, say what happened. It's still very, very difficult," she said.

Her therapist told her she was so focused on looking after the needs of her family that she wasn't grieving.

"I just felt that as long as everybody around me was OK, I am OK," Jean said.

She said her therapist asked her, "What about you?"

"I told her I didn't know, I just didn't know about me."

Preparing for the trial

In the days after the shooting, protesters in Dallas chanted Botham's name in the streets.

At the time, civil rights attorney Benjamin Crump, one of the Jean family attorneys, called it an egregious example of the constant threat of deadly violence African Americans live with.

"We're still dealing in America with black people being killed in some of the most arbitrary ways, driving while black, walking while black, and now we have to add living while black," he said last year.

Jean said she also believes Guyger would have acted differently if Botham were white.

Listening to the 911 call, Jean said she felt Guyger seemed more concerned about losing her job than about Botham. Jean and her husband have also filed a federal lawsuit against Guyger and the city in October, alleging the former officer used excessive force. A judge granted a stay in the civil case until the completion of the criminal case, said Daryl K. Washington, a Dallas attorney who represents the Jean family.

The main entrance of the Frank Crowley Courthouse in Dallas, Texas, where Amber Guyger's trial will take place.

In her therapy sessions, Jean has focused on what she could expect to happen in the courtroom, so she won't be surprised. She knows she will likely hear the 911 call again.

The therapist didn't tell Jean how to react to each scenario, but asked her what she thought she should do. If photos of Botham's body were shown in court, Jean said she could close her eyes, or turn away, or decide that she can confront it.

Kimi Nolte, the lead victim services coordinator at Victim Support Services, a Seattle based nonprofit, said the families she accompanies to court for homicide trials fear seeing the pictures of their loved ones.

"A lot of families end up being unable to stop imagining what the last minutes of their loved one's life was like," said Nolte, who is not involved with the trial. "Were they in significant fear? Were they in a large amount of pain?"

"And to hear about it in court, it might just validate what they suspect all along," she said.

"Trial has a way of bringing everything right back up again. Their grief is going to feel refreshed -- like they hit a refresh button on their internet browser," Nolte said.

To prepare her clients for court, Laura Takacs, a clinical social worker in Seattle, teaches them grounding techniques to soothe themselves when they see or hear difficult things.

She encourages them to give a victim impact statement, because they will have a captive audience to describe who their loved one was. She also suggests that clients find out the order of testimony from attorneys, so they can decide whether to step out of the courtroom.

Trauma "reverses things that you thought were true about the world, the way you view the world," she said.

"It is so important to give every opportunity for the survivor to restore some level of control, control in what they hear, control in what they see, control in their ability to be able to respond," said Takacs, who specializes in helping people cope with sudden, traumatic deaths.

Washington, the attorney who warned Jean about the 911 call, said he has tried to "prepare her slowly" by discussing scenarios she might encounter in court.

He has talked about the second-degree murder conviction of former Chicago police officer Jason Van Dyke, who is white, for killing Laquan McDonald, a black teenager, to encourage her to have faith in the American judicial system.

From left, Botham Jean's father, Bertrum; brother, Brandt; mother, Allison; and sister, Allisa Findley

Jean set aside her Saturdays to pray for justice, and fast to strengthen her faith.

She prays for Guyger "to be truthful," and for the prosecution to "represent our interests effectively."

For her family, especially her children, she prays for "courage to deal with the trial and acceptance of the outcome."

As she prepares, Jean says her son's encouragement to look on the bright side will guide her.

"I'm just trying my best to focus on God being the ultimate judge," she said. "And whatever the outcome is, then that's His doing."

On September 6, the anniversary of Botham's death, jury selection began in Dallas.

Her brother's keeper

When Jean's daughter, Findley, learned she would be a prosecution witness, she started to tremble.

She still trembles every time she thinks of Botham's death.

"We were a team, the two of us," she said. Since Botham was shot, "it feels so dark, and I feel alone without him."

Botham attended Harding University to be closer to Findley, who had moved to the United States. The two spent most Thanksgivings together. He called to apologize when he couldn't make one Thanksgiving, she said.

Findley listened to the 911 call nearly a half-dozen times. She said she heard Botham suffering in the background.

"I always thought because he was shot through his heart, I always assumed that he died on the spot," she said. "It bothered me that he suffered."

Like her mother, she has worked with a therapist, and she prays several times a day that Guyger will be found guilty.

"We're always taught to ask God for exactly what you want, so this is what I want: I want justice for Botham."

Now she is getting ready for court, preparing "for the first time I see his killer."

"Anything else, I'm ready for it," she said. "I am my brother's keeper."