This is in the state of Florida.
So I am in my room very mad at my mother and playing loud music in my room. She tells me to turn it down and I do. She's not happy with how much lower it is and tells me to turn it down lower and I tell her no that I already did. Then she starts yelling and I get sick of it and I turn it down substantially. Then she's still not happy and unplugs the whole radio. I get it back and plug it back in and turn it back on. She then walks across the room, grabs my bat (I used to play softball), and tells me to "get the f*** out of the way". I said no and that she did not buy or give me my radio so she can't take it away. At this point in time I am standing between herself and my radio leaning on my dresser with my hand resting on the top of it (the dresser). Next thing I know my mother swings the bat straight up into the air and straight down on my hand. I yell and call her crazy then go down the street and try to find someone with a phone.
About 15-20 minutes later I am back at my house speaking with a police officer and paramedics. My mother lies and tells the police that she was trying to hit my radio and I moved my hand in the way causing me to get hit. Then she says she was just trying to hit my dresser to scare me and I moved my hand in the way. My prior thread tells about her pressing Domestic Battery charges on me for defending myself, and the police officer saw this and did not believe a word I told him. He simply ROLLED his eyes at me. I was then taken to an ER and they found no broken bones. Just a contusion and severe bruising. The police officer tells me I'm a lier and continues to be rude and role his eyes at me in the emergency room. I am then told it was an "accident" so I'd be going home with my parents who just almost broke my hand over music and I couldn't press charges. This is the third or fourth time the police have been called due to her hitting me and still nothing is being done other than myself getting charged and arrested.
I am a minor. What can I do? How do I show them the truth?

