The woman accused of killing two of her lover’s children in April by setting fire to their South Boston rowhouse was ordered held yesterday on $1 million bail. Nicole Chuminski, 26, of South Boston wept in Suffolk Superior Court as she pleaded not guilty to torching Anna Reisopoulos’ West Sixth Street home April 6, killing her two daughters, 14-year-old Acia and 3-year-old Sophia Johnson.