You must tell your parents immediately. They have to know what is happening with you. I totally agree, you also must find someone to talk to about this, preferably a therapist. Are you on any psych meds? It's possible they could help you. I agree that you sound like you are in a major depressive episode. If you are ever actively suicidal again, dial 911 and go to the ER. You do not want to commit suicide. And that is coming from someone who is suicidal all the time. It's not the answer. It is a very permanent solution to a totally temporary problem. So, don't ever do it. You have the rest of your life ahead of you. You will do amazing things. You just need help, like everyone else on PC and probably half your classmates.

I have bipolar disorder type 1, but my first major depressive episode was when I was seventeen. It was awful but I got help and I pushed through it. I have done some really cool things in my life. You will, too. Just don't give up. Tell your parents and get a therapist. And don't be ashamed. All the cool music stars and people in Hollywood have major life issues and therapists and psychiatrists and a lot of them are on meds. And they still accomplish a ton. So, keep after it. Don't throw in the towel. You can do this.