If you're contemplating suicide, you're not being silly, you're just having problems in your life and you need professional help.
I can understand your need to tell your friend about your feelings, but i dont think it was the best thing to do at the time. You need to talk to a professional that will be able to help you, and i doubt your friend is a professional in this area or has dealt w/ it very often.
You need someone to talk to, and it has to be someone that can be objective. As much as they try, friends and family members often aren't objective enough to be of much help.
How about going to talk to a school guidance counselor? S/he'll be able to help you out, or direct you to someone else that will be able to.
Also, whenever you're feeling suicidal you need to get help ASAP! If you don't feel you can talk to anyone about it, just go for a walk and seriously think about what you'd be doing ... I've read somewhere that if a person can find something to occupy their mind for about 10mins, the suicidal feelings will pass and they're often out of danger (however, this is only temporarily). I don't know if this is actually true, but i know it's happened to me, personally.
Best of luck,hun. Let us know how it goes.