robert dellinger , 54 , allegedly tried to kill himself in december 2013 by driving across highway , but instead he killed a young couple .
amanda murphy , 24 , and jason timmons , 29 , were killed instantly in the crash in lebanon , new hampshire .
murphy was eight months pregnant with their first child , a girl .
dellinger pleaded guilty in february to negligent homicide for their deaths , and to assault for the death of the fetus .
he faces 12 to 24 years in prison when sentencing resumes thursday .
deborah dellinger , defendant 's wife , described her husband from the witness stand as a ` man of ethics , integrity and friendship '