robert dellinger , 54 , was sentenced in court on thursday .
amanda murphy , 24 , and jason timmons , 29 , were killed instantly in the crash in lebanon , new hampshire in december 2013 .
investigators said dellinger was depressed and drove his suv head-on into the couple 's car on purpose .
murphy was eight months pregnant with their first child , a girl .
dellinger was given credit for the 15 months he has already spent in jail .
he could could be out of prison in less than eight years .