A 37-year-old Leominster woman killed in a car crash last month is being remembered as a devoted mother, wife and cancer survivor. Crystal G. Johnson-Clementi, 37, of Leominster, formerly of West Boylston, died on Feb. 20 from a car crash. She left behind her husband of seven years, her son, two sisters, two brothers and several nieces and nephews, according to her obituary.