My sister is a threat

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I live with my mom along with a few other siblings and I have one sister who doesn’t get along with anyone. She continually terrorizes me or someone else in the household. Yesterday she started a fight bc she kept ramming the door into me while I was sitting there trying to build a shelf and then she tried to attack me bc I cussed at her so I spit at her and she was going to attack me again but I locked myself in the bathroom before she could. She started throwing tools at my other sister who was just there so when she went to the bathroom we had to make sure she couldn’t get out by tying the door to the panel and she kept breaking the door and then proceeded to shower. We thought she may have cut her self bc she wasn’t responding and the bath was running for a long time and before the shower she said “ if there’s now way out I might as well kms” so we had to untie the door from the panel and check on her but she was fine and she kept starting drama throughout the day and we all tried to get the cops involved but they wouldn’t show up bc of all the other times they showed up to her dumb nonsense. I had to sleep w the doors locked bc of all the times she threatened to kill me and I woke up to her yelling at my sister for making noise by walking around in her own room. She tried to come into my room after that but it was locked so she made the fire alarms go off throughout the house. I’m scared to be alone with her bc she has overpowered me before and she’ll fight til someone dies bc she has stabbed my younger sister with a pen 6x in the thigh all bc she wanted take the knife out of her hand so she wouldn’t kill my other sister. Idk what to do or how to get rid of her bc my mom doesn’t won’t kick her out and my other sister who got stabbed never pressed charges. I just want her out of here