If you are acting undignified and know it, then knock it off. You may be thinking, “But she is so mean to me.” Do not play into that; two wrongs do not make a right, and you are not only acting undignified, you are an adult who is setting a poor example for a child. If you recognize you have been acting atrociously, stop what you are doing and apologize to everyone who was affected by it. That may mean you apologize to your stepchild, your significant other, and the ex. Even if your negative behavior was nothing in comparison to something she has done to you, apologize anyway. You have behaved in a way you would not want your stepchild to mimic, so you should try to rectify the situation by apologizing and explaining to your stepchild that you let your emotions get the best of you and acted in a way you wish you hadn't. It may feel awful while you are apologizing, but in the end you are the one who is acting with self-respect and respect for those around you. This will gain the respect of others and perhaps help them look at their own actions and see how they have behaved in unhelpful ways.