Got in fight, arrested, have court?

Okay so this is what happened, on thursday my sister and I fought because my mother was beginning to have a panic attack which can sometimes lead to her having a heart attack, I had barely arrived home but with one of my friends who she dislikes which is a saint, she has that all twisted, we lack communication but I can't talk to her, she starts yelling and im not one to argue! My sister came upstairs to me and started yelling at me, cussing me out saying my mom was going to die because of me, (my mom has GAD and I literally don't do anything to her, im in my own world im always the bigger person and walk away when she begins telling me things) The neighbors had called the cops for disturbance and were apparently in my house before my sister and I even foght, when we fought (lasting about 5 seconds) I did hit first, she wouldn't stop yelling and I just snapped, the cops ran up the stairs and seperated us! I was arrested and charged for battery and resisting/delay (which I wasnt even aware the cops were there and pulling me apart) I stopped instantly so I was pretty confused but okay! I did hit first and now i have court in two weeks, do I need a lawyer, if so how do I get one? I don't have a family lawyer, what do I do? Im really new to this and somewhat scared I guess, also im 19, if that matters, in California! Any advice??