An Oklahoma mother who had been imprisoned for 15 years for failing to report to authorities that her boyfriend was abusing her children was freed from custody on Friday.

Tondalao Hall was sentenced in 2006 to 30 years in prison under Oklahoma's "failure to protect" law after her then-boyfriend, Robert Braxton Jr., abused two of their children so severely, at least one had multiple broken bones, according to Hall's attorney, Megan Lambert of the American Civil Liberties Union of Oklahoma. Hall had already been in jail for two years when she received her sentence.

Tondalao Hall in 2019. Oklahoma Department of Corrections via AP

Braxton, meanwhile, pleaded guilty to abusing the children, but was given no additional time behind bars: He received a 10-year suspended sentence and was released on probation after having served his two years in jail, Lambert said.

The discrepancy between the two punishments prompted widespread outrage and put a spotlight on Oklahoma's high incarceration rate, which is the highest in the country. The state also has the highest rate of female imprisonment.

Hall was released around 11 a.m. local time from Mabel Bassett Correctional Center in McLoud, Oklahoma. Wearing a silver jacket, she stepped out of the prison and into the arms of family and supporters awaiting her, some holding pink and purple balloons.

When asked by a reporter how it felt to be free, Hall responded through tears, "Wonderful."

"I'm blessed," she said. "I'm blessed and I'm humble."

Ahead of her client's release, Lambert told NBC News on Friday that it was a "bittersweet" day.

"I am relieved that we finally got some justice for her, but at the same time, it’s a little bittersweet because today is coming 15 years too late," Hall said. "And at the same time, she’s still leaving behind countless other women who are still incarcerated on failure to protect charges."

Oklahoma's incarceration ranking is one many state officials are eager to shed. On Monday, more than 400 inmates across the state were released from prison in what the governor said was the largest prisoner commutation in U.S. history. The inmates had been sentenced for drug possession or other nonviolent crimes.

Hall got her break last month when the Oklahoma Pardon and Parole Board unanimously voted to commute her sentence. Republican Gov. Kevin Stitt granted the request on Thursday, which Hall said came as a surprise to her.

"I was shocked, thankful, appreciative that I could be with my family," she told reporters of the governor's decision as she walked out of prison.

Lambert said Hall's years-long journey is "representative of an institutional misunderstanding of domestic violence."

While every state has laws to protect children, only six have "failure to protect" laws or similar child abuse statutes that carry a possible life sentence for parents who don't report abuse, according to the Associated Press.

Oklahoma’s law makes no exception for parents who stay silent out of fear for their own safety — which Lambert said was the case in Hall's situation. In addition to choking and punching their young children, Lambert said, Braxton beat and psychologically abused Hall.

"What should have been a mitigating factor, the fear that she was feeling of her abuser, was specifically used to enhance her sentence."

"What should have been a mitigating factor, the fear that she was feeling of her abuser, was specifically used to enhance her sentence," Lambert said.

Hall was just 19 when she was arrested. While the child abuse charges against her were dropped, she still pleaded guilty to enabling child abuse.

Her three children, who were raised by Hall's cousin, are teenagers now. Lambert said they are "really excited to be able to build a relationship with their mother for the first time in their lives."

Robert Hall, Hall's 16-year-old son, was among those who greeted her upon her release.

"I’m feeling great. I thank the Lord for this day," he told reporters outside the prison. The plan for the rest of the day, he added with a smile, was to "have fun, go out to eat."

While she was imprisoned, Hall maintained a relationship with her children and got her license as a cosmetologist.

“I’ve worked really hard to be the woman my children need me to be," she told the Oklahoma Pardon and Parole Board last month when the board was reviewing whether to commute Hall's sentence, according to NBC affiliate KFOR in Oklahoma.

Hall said she hopes to see more women behind bars follow in her footsteps. When asked what she plans to do besides spend time with her family, she said: "I'm looking forward to helping other ladies.”