Fight & cops

My mom and sister got into a big fight tonight. My mom is currently homeless and was staying at my house. She picked my sister up from her high school ball game and she started yelling at my sister. My sister naturally defended herself and my mom starting hitting her and pulling her hair and stuff and calling my sister names and shiz. I was asleep when they got back to my house and I heard the last of the fight when my sister finally hit my mom back after taking several blows tonight. My mom got pissed and said she was going to kill herself and drove away in her car with her boyfriend. She told all her stuff was ours and then stopped answering. I was worried so I called the cops to help find my mom. My mom has a record and bad experience with the cops and CPS and is now pissed at me for calling the cops. She says if she goes to jail that she will never speak to me or see me again. My sister is fine, she is sleeping on my couch. My mom has answered me and is fine, just mad. I am so stressed out. I am trying to convince my sister to just live with me, but her school is 20-30 minutes away from my house and no buses come this far and she can't drive yet. I told her I would take her daily, but there is lot more to this situation that it's too long to add all here. But I'm so stressed and don't know what to do.