A woman accused of killing her 2-year-old son at their Eastvale home must stand trial on charges of first-degree murder and assault on a child resulting in great bodily injury or death, a judge ruled Wednesday. Xiu Xiu Sun, 35, allegedly killed Chris Cui in October 2022. Following a preliminary hearing Wednesday, Riverside County Superior Court Judge Timothy Freer found there was sufficient evidence to bound Sun over for trial on the felony coun…