I'm sorry to hear that you are in a difficult and stressful situation. The police are filing charges based on the information and evidence that they are able to gather. In this case, it sounds like someone, probably your mother -in-law, is telling the police that you were the one who assaulted her, not the other way around. As a result, you were charged, as well as your mother-in-law. It is probably very difficult to simply get these charges "dismissed" at this point, but you need to...