alton hines , the fiancé of leah o'brien , 33 , the beloved teacher killed in a car crash on april 25 , is speaking out about the night the woman died .
the other driver , 19-year-old ramiro pedemonte is facing charges including homicide , reckless driving , and serious injury by motor vehicle .
police determined that pedemonte was going over 100 mph when he hit o'brien .
authorities say pedemonte was on probation at the time of the accident with a june 2014 charge of of possession with intent to distribute .