An intoxicated Bronx public school teacher was arrested by cops yesterday after she crashed into another car early in the morning. In a scene out of one of those DWI PSA's, police found discarded, empty Bud Lights in the backseat of the rental car being driven by Anna Marinelli, 27, who teaches first grade at PS 21. Another female bolted from the passenger seat after the crash, which occurred on East 181st Street near Grand Concourse in Fordham around 9 a.m. Marinelli, who was using a rental car because she had totaled two other cars in the past month, was charged with a DWI. She allegedly told police she was only guilty of being a good friend, since she was trying to help her friend find drugs.