i really need your guys' help...

Try not to make bad decisions....but honestly, I've made several in the past week. We all have bad days/weeks, so just try not to let that happen again. And if your best friends hate you for how you are changing, then that's their problem. They should appreciate you for who you are, not hate you. But sometimes they just act that way, even when they appreciate you for who you are. So don't let that bother you.

Listen to music.
As the old saying goes..

Just focus on what makes you happy =3

Follow your morals. Do what you know is best.
Every pain and stress is difficult, and hard to overcome. But it always subsides, and the storm always passes, and you're always stronger when it does.
Get your parents to trust them, show them that you can be trusted and that you learned from your mistakes and bad decisions. If your friends leave you for it, then so be it. If they leave your for changing in the first place rather than supporting you, then they aren't what you need to begin with. It may be lonesome, but being alone and having strength in yourself is far better than being with friends who beat you down and feel worthless.
It's hard, it's difficult, and it's hell, I know. But you can make it out of this, and you will get stronger from this if you let yourself.