I moved out of my mom's house...Now my sister thinks she's my parent?

So, I'm 19 and I just moved out of the house a little under two months ago. I moved into a place that I'm renting with my sister and two of her friends. My sister is 8 1/2 years older than me and now that I've moved out of my mom's house, she thinks that its her responsibility to parent me. We're sisters, she's not my parent.

I don't really know what to do about it. Every time we try to talk to each other about anything of the sort, it gets blown into a huge argument and never gets resolved. It feels like I'm always mad at her and we always have an attitude towards each other and its really starting to tear apart our relationship.

No, I haven't made the smartest choices within the last month but I don't feel like its her place to yell at me for it and tell me what to do. In fact, she even tattled to my mother. I'm an adult and I'll make my own mistakes.

I just don't know what to do anymore. She feels like I don't have her back on anything and I don't feel like I can trust her with anything anymore. What can we do to resolve it?