I'm going to start by saying, holy crap is this stressful. I've read lots of books to help me understand the step mother roll. But  holy moly. My step daughter whom is 5, has been acting out like crazy lately. Shes on a week on, week off, 50/50 custody agreement between my man and his ex girlfriend. Anyways, when I first assumed the roll it seemed pretty easy. She would come back from her mothers. The first couple days would be rough then she would behave. But lately shes acting out all the time. Shes not listening, she argues everything, shes been throwing tempertantrums, kicking, screaming, lying, sneaking around, stealing and straight up being defiant and it's not just to me. However, it's definitely worse towards me. She's testing boundaries and pushing everyone to their witts end.  I understand shes probably going through alot.  Her mummy and step daddy have been fighting lately and she feels it's her fault. Which we try and calm her by letting her know it's not her fault, that if they fight its between them and not because her and that she cant control that. I also understand that her mother doesnt say very nice things about me. Which I know because she repeats them on broken record mode at me. Shes even told me to jump out of the window of the truck when we were going 110km down the highway to get home. It doesnt feel nice. Idk I'm just stressed out and feeling like I could use a little love and acceptance right now. :(