My Child - The Documented Offender

I am ticked. Honestly, I feel blind with fury. I am hoping to vent here. Maybe feel a little better. Maybe reason through some of this. If you are looking for rainbows and sunshine today you should find another blog.
I went to pick Carson up from preschool today. When I entered the room one of the teachers quietly asked me to stay after because she needed to talk to me.
When most everyone was gone she prefaced things with, "This really isn't a big deal, and I have already talked to Carson, but he drew something that "offended" someone." My stomach was immediately puddled in my feet. I wouldn't think Carson would do something to render him a school district offender but obviously this was serious. The teacher briefly showed me photocopied  mural Carson had drawn for another little girl in the class. Here it is in detail:
There was a large boat, a pirate ship with multiple characters. Over on the left, there were two stick figures. Over on the right, there were pirates. They had bandanas, furrowed brows, and swords. Over one of their heads was either a thought bubble, or word bubble (couldn't tell) that said, "Kill Jane" (I have changed the girls name).
I honestly couldn't figure out what the problem was. The teacher then explained the picture to me. Carson and "Jane" were on the left, and he was trying to save her from the pirates who wanted to "kill Jane". I was STILL confused at this point. Maybe I am dense, but I didn't see any problem with the picture. The teacher then pointed out the bubble and said, "this is the problem". She couldn't even tell me why it was a problem. All she said over and over again was that it was what "offended" Jane's mom so badly.
Jane's mom had freaked out, photocopied the photo and brought it to the attention of the school. She couldn't even explain why she was offended; she just was. She had also instructed her little girl to tell Carson not to draw her any pictures anymore because they are bad (Jane and Carson have been exchanging MANY pictures all school year). Frankly, I am relieved. I don't want Carson to have anything to do with the girl because obviously her mother doesn't have enough to do and is easily excitable, thus resulting in the current situation. As a result, she is picking on my child and I am ready to attack. I know that is not the Christ-like response, but this mother bear is seething.
I understand bad things have happened in the world. And I understand bad things have happened here in CO. I also feel like people get attention for drama. I think morals, perspectives and people are screwed up. Unfortunately, if a five-year-old writes the word "kill" on behalf of a pirate he is trying to save his friend from (oh, and by the way, he told me he only wrote "kill" because "throw Jane in the water" wouldn't fit in the bubble), he is a menace to society. However, kids/people in general copulating all over schools is ok, even encouraged. I don't get it.
Now I have to make sure he doesn't even tie his shoes wrong. Grrrrr.
I know what the answer is. Accessing it for me seems far reaching right now, but the only way to change and heal is through the Atonement. I know the anger I am feeling is not God-given. Guess I better start praying like life depends on it because in truth - it does.