PONTIAC, Mich. — The mother of the Oxford High School shooter told coworkers she felt like she was “failing” as a mother after she met with school officials the morning of the shooting to discuss concerning statements and drawings her son had done on a math worksheet. Jennifer Crumbley, now on trial in Oakland County Circuit Court for four counts of involuntary manslaughter in connection with the 2021 shooting that left four dead, confided in both her boss and a coworker about her feared failures. She also shared with them photos of the disturbing worksheet that included pictures of a gun and …