We are glad you are reaching out for help today. You mention in your e-mail that you think your friends wouldn't care if you died. If you are feeling suicidal you need to talk with someone. You can talk with your Mom or Dad, a teacher at school or counselor. Suicide is not the solution to your problems.
What is making you feel like you have to live up to everyone else's standards? You need to be able to make yourself happy before you can make others happy. Your true friends are going to be your friends because they like you and they don't expect you to act or be a certain way. If your friends are wanting you to act differently then maybe they aren't your true friends.
You said that you feel like you are your best friend are drifting apart. Have you talked with her about how you are feeling? If you are worried about your friendship then talk with your friend. Let her know how you are feeling.