It’s hard to answer questions like this without more details. Knowing how old you are, your social status (child living with parents, single, married etc.) and where you live would be helpful. Without those specifics all I can say is that you need to seek help.
Help can come in many forms. If you are a child, of course you should talk to your parents. However, if this isn’t possible for whatever reason, find an adult in some position of authority who will be willing to listen to you. This may be a teacher, a leader of your church, your doctor… Any of them are in a position to assist you.
If you’re an adult and you’re able to seek help, you might want to begin by talking to your doctor. They’re not a specialist, but they should be able to at least have a general conversation about what’s going on, and hopefully refer you to someone who can offer you specific assistance.
No matter your age, if you are in the United States and things are getting bad, simply go to the nearest phone and dial 911. This may seem intimidating at any age, but if you’re a kid the first thing I’d worry about is “won’t I get into trouble?” No. You won’t. That’s exactly what 911 is for. You don’t need to ask anyone’s permission to do this, not even your parents. Give the operator your address and tell them clearly that you are mentally disturbed. You need help. Now. The operator won’t judge you. They’ll ask why you think this, and if you’re going to hurt yourself or someone else. Be honest, but be firm. Clearly repeat that you need help.
If you call 911 things will start to move quickly. Take a deep breath and try to remain as calm as you can. What will probably happen next is that either an ambulance or a police car will arrive (sometimes it’ll be both). Sometimes they’ll have the lights and sirens going, sometimes not. Don’t worry, you have done nothing wrong. At all. If you didn’t tell anyone and someone else is in the house (assuming you’re in a house!) they might be a little surprised but don’t worry. This isn’t about them. It’s about you. The paramedics / cops / firemen or whomever will find their way to you. Again, they’re not there to judge you – just be as calm as you can, tell them exactly what’s going on and why you called. If you’re intimidated by someone at your location and you’d prefer to speak in private, just tell them. They’ll make sure you’re in a safe location to talk.
No matter your age, location or situation I’m glad you’re reaching out. Keep going. Fighting through something like this alone is incredibly hard. Reach out and get the help you need.
I wish you the best.