By Sam Truelove The heartbroken mother of Audrii Cunningham, who was found dead in a Texas river, has insisted she “failed” her daughter. The 11-year-old schoolgirl was last seen near her home on Thursday, February 15 but she never got on the bus to take her to school. Her family later reported her missing and a painstaking search came to an end on Tuesday after her lifeless body was found in the Trinity River in Texas. Don Steven McDougal, 42, who is a friend of the girl’s father, has been charged with capital murder, court documents show. Audrii’s devastated mother, Cassie Matthews, took to …