When a Stepmother oversteps her boundaries?

When do you think that a step mother has overstepped her boundaries? My ex-husbands wife needless to say think I don't exist. She is constantly telling my little girl that she has to call her mom and that by calling her name or Miss name that is disrespectful. She often tells my child that it gets on her nerves when my child calls her by her name when speaking with me instead of calling her momma. She is talks about me to everyone around her trying to get them not to talk to me like she is Junior high and tells my daughter that I do bad things. What gives? What would you do in this situation?