It is incredibly difficult to talk to someone; been there done that. It's so simple for me to say "talk to your school counselor" or "talk to your parents" etc etc etc. It's not that easy! Do you have a friend that you trust and that you can talk to? If so, start off with small things and go from there. Don't like totally spill your guts all in one sitting becuz that can be overwhelming for yourself as well as your friend. Have you ever tried calling a crisis hotline?
I can also tell you not to feel ashamed or weird or silly to tell someone how you're truly feeling inside. It's hard not to but, for instance, if you're talking to a friend, he or she will not think that you're weird or full of it. They will support you and be a FRIEND to you. If they do "diss" what you say, then they aren't a true friend, right?
Bottling everything up inside of you is not healthy by any means. It's not a good thing to do. Do you do any kind of journaling? If not, give it a try. Write down all of the things that you are feeling, thinking, the things that are running through your head and get them out on paper. If you want someone to actually read it and see it, post it in here. Vent your heart out! Venting is good for you!
Anyways, keep your chin up. Hang in there. Take care.