Ex has a crazy girlfriend

My ex currently is in a relationship with a woman that poured stuff into my gas tank, broke windows from his car, made fake profiles on Facebook with photos of our dead baby, and even tried breaking into my home. I currently have a two year old child with this man and I refuse for our son to be near her due to the things she has said and done. I’m scared she will try and harm our child. Am I wrong to keep him away from her?