Why would my neighbor call me a racist?

Something from a few years ago has been bothering me lately... my old neighbor just friend requested me on Facebook. A few years back while my ex and I were stationed at Fort Polk, my daughter (we are white) had this cute little boyfriend/girlfriend thing with her son (they're black). They were both 8. A few weeks later, a new kid moved onto our street, so I sent my girls over with cookies for him and his sister. My little girl's "boyfriend" (I'll call him Kane) rode by on his bike while they were all having cookies, threw his bike down and started screaming at my daughter, calling her a "ho" and ordering her to get away from the new boy. Before I could get to them, Kane had grabbed her, slapped her and thrown her down (again these kids were 8 years old). Kane's mother saw the whole incident. Later on, I walked my daughter over to Kane's house so she could tell him they weren't friends anymore. Imagine my surprise when I was called a stuck-up, racist b-word by Kane's mother, who then promptly started telling everyone that I made my daughter break up with her son because he is black. No one believed her because too many of the neighborhood adults saw the incident, but it hurt. Can anyone tell me what I should say to her now, four years later?