You have come to the right place to talk about those feelings...most of us have been where you are now so we do "get it"
Manda, there are stickies at the top of the forum that I hope you'll read..What to do if you're feeling suicidal...and Pters wise words.
Take a deep breath and remember that you are talking about a "forever decision" and our lives change...given time they do...but you have to be alive for it to happen.
Keep talking..this is a wonderful place for support but people can't help you if they don't know how you feel.