Aw, hun. I'm going through the same crap. Know what really helps? Talk to someone. If your parents won't listen, try a teacher. Or if it's available in your area, call 2-1-1. They're an anonymous group of volunteers who will give you advice and help with your stress. But if you mention suicide or anything along those lines, they will call for help. They're a wonderful group of people and if available where you are, I deffinitely recommend giving them a call!
But what I do, besides the 211, is sit down with my mom. I just tell her everything that is on my mind. A good cry will help. You just need to let it all out and have someone to listen to you.
Don't hold back, it can make you feel worse. You'll do fine, have fun at graduation