Apparently she has done this to him dozens of times. She is trying to get him arrested. They are both horrible human beings.
Feel like it was established last summer that both parties are pretty sad individuals.
That being said, he appears to be at fault here based on what is reported. Even if she did prevent him from seeing the kids the night before, he shouldn't have done it. His attorney claims she was in contempt of court. Surely, the attorney filed papers in court since the two have such a troubled relationship.
The act itself is problematic because the report indicates he didn't even have contact with her. The school called the cops after having some sort of incident with him.
She isn't a model citizen herself, so there's the chance she set him up by having him come to the school after already telling school personnel a story about something he had done.