Attacked by Roommate's Ex-Wife

What is the name of your state? CA

I rented a room from 'BOB' at his house. I'm a college student, I don't talk to anyone, and I keep to my room. He and his ex-wife had a party and I told one of their guests that if they were to use my restroom to keep it clean. A few days after, the ex-wife approached me and asked me why I yelled and cussed at her friend. I said that I didn't and I'm sad that they got upset over this overamplified miscommunication. The night after, she brought another friend and they both attacked me. Fortunately I didn't suffer any serious injuries. The El Monte city police came and I said I wanted to press charges. The ex-wife had left by then. The police made me feel that I wouldn't get anywhere with proscecuting her b/c it'd be a bunch of verbal bantering... and they left. I haven't gone to the department to file a report b/c I've been trying to pick up school and many of my friends and family have told me that as long as I'm safe now, everything's okay and that karma will get her. After some counselling and talking to friends, I believe that she was out looking for trouble with me because I was living with her ex-husband.

Now that most of my life is "back on track" I've been contemplating about how it wasn't okay for her to attack me and that I should let the DA determine if she has committed a crime. Is there anything I need to research or look into before I file a report at the department?

FYI, I moved out of there the next day. And this happened 20 days ago.