Jeannette Clements says her daughter is innocent of murder, claiming that she struck her husband accidentally as he rode his motorbike alongside her car at night.
Nicole Reyes, who has two children living with their grandparents in Rumney in Cardiff, could face up to 30 years in prison if found guilty of her husband's murder.
"Sometimes you just feel as though you can't even cope - and it's the same with my daughter," says Jeanette.
"She has her good days and bad days, but she's getting more bad days now as time goes on, because we didn't expect it to go on for this length of time."
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A cold and windy day across Wales with sunny spells and showers of rain, sleet and snow
An inquest is to be held into the deaths of four family members who died when their car was involved in a crash near Aberystwyth in June.
Cold and windy with sunny spells and showers of rain and snow.