How do I talk to my friends about how I'm feeling?

It started as the shock that the girl I like had picked another guy. which shouldn't be a shock at this point, but the fact that a close friend of mine is defending the guy. The guy in question had a bad temper, but according to my friend he didn't mean it and I was being jealous. Then my racing thoughts just began to question everything. Would anyone care if I died, would this girl in particular, does my life have any meaning at all, am I a bad person, are all my friends really lying to me when they say they care about me, or am I just being used because I'd do anything for them. Hell I've started to wonder if they'd all be better off if I died, and that's starting to scare me. I don't even know how to vocalize by problems to my friends.