At 14, I shared my feelings of suicide with a teacher.
I certainly behaved much differently than I felt in the beginning. But, sharing with the teacher, then the counselor, was the first step in my seeing a psychiatrist and getting a major depressive disorder diagnosis. A year later, after psychotic and manic (mostly mixed) symptoms, I was diagnosed with Bipolar Disorder.
Anyway, I share this to let you know there is help available to you if you reach out. As others have mentioned, if there is a teacher you trust, that is a wonderful place to start. It is so hard to deal with those feelings when you are so young. I remember. I lost a lot of friends and I never understood why. It took time for me to understand that people just don't understand. However, those who stand by you, will continue to do so and you can trust them. I wish you the best. Please continue to come here and share as much as you need. You need support. You will find it here.