My fiance and his daughter drive me crazy!

So my fiance has a 5 year old and a 2 year old. The 2 year old is good but the 5 year old basically gets away with everything from her dad. she looked at me smiled and stomped on my foot on purpose other day and my fiance (her dad) just says o she's just playing. I tell her not to do something and she continues doing it (even after she was told repeatedly, yelled at to stop, and got a butt whooping) or she runs to her dad and he lets her get away with it. He doesn't discipline her and when I try to tell him to help me with discipline he shrugs it off or we end up in a fight. She has gotten frustrated playing a game on a phone and threw it across the room as well as her shoes across the room. My fiance leaves for work every day telling me to try to get along with her. I feel like I'm the only one doing everything (cook, clean, take care of kids) and he just says well I'm working. Then tells me I'll never be able to handle having my own kids if I can't handle her. He comes home and either goes outside or has friends from work come over and is outside w them all night. He doesn't help me like he used to and I don't know what to do anymore. Any advice?