LOS ANGELES (KABC) -- A 72-year-old woman has been sentenced to prison after accepting a plea deal Thursday in a hit-and-run in Hawthorne that killed the 15-month-old boy of MMA fighter Marcus Kowal Kowal and wife Mishel Eder never imagined they would be in this position."Because of her, my wife cries herself to sleep almost every night," Kowal said in court.Their young son Liam died after being struck by Donna Marie Higgins in September 2016. She pleaded guilty to vehicular manslaughter, a deal that places her behind bars for six years.Allison Bell, Liam's aunt, survived the impact."There is so much anger I have for her, but soon after I think about everything she did, that anger is replaced by the emptiness I have for losing my baby nephew," Bell said.Both parents relived the pain in court."Doctors told us there was no neurological response but on occasion, his tiny fingers would twitch as I held his hand, Eder recalled. "We were told those were nerves misfiring -- that was a special kind of torture."Higgins, at times, closed her eyes and appeared dazed in court."Not once has she tried to reach out to apologize, not once has she shown any remorse," Kowal said.Despite their loss, Kowal and his wife are doing what they can to move forward while keeping Liam's memory alive.Just two weeks ago, Eder gave birth to their second son, Nico."Liam will always be a part of our lives, and Nico will know exactly who his big brother is," she cried.