My mom is crazy (trigger warning for people uncomfortable with mental abuse)

The other day my mom and I got into a big argument because the night before, I told her that I'd been feeling uncomfortable around my stepdad and that lately my Bipolar Depression has been making me really stressed. She asked me if I was sure I felt uncomfortable to which I told her I was. The next day on the way to school she tells me "you know his kids are gonna hate you right?" Which pissed me off so much and we started arguing in the car. When we dropped off my little sister she threatened to send me to the mental hospital and drove me home.we sat in the car still arguing and she took my phone and called my bf to try to embarrass me so I hung up the call and threw my phone ( which I shouldn't have done, it was stupid) she shoved me in the house by my hair and went into her room, grabbed her gun and place it on the computer table by the door and screamed at me to shoot her or shoot myself. She apologized and has been acting like nothing even happened. I dont even know what I should do anymore, I'm only 16 so it's not like I can just leave and I dont have any family to go to. I just cant anymore.