I think I'm depressed. My life is messed up?

Hi, I think I need your help. Right now I'm really losing hope in everything. I've already lost all faith in humanity. My life is messed up :/
Well basically this is what happened: From 6th to 9th grade, I had been making straight As in school, and my work ethic was superb. But in 9th grade, I began to like a girl… ever since then my work ethic has been terrible. I finish papers late, don't study for tests, always think about that girl (not anymore, because I don't like her anymore), and my grades have suffered tremendously (many Bs, almost Cs – for me this is REALLY depressing, because I feel like I am very smart and that I should be getting straight As, and no one understands me :( i'm hopeless) – this is obviously because I divered my attention from schoolwork to my love for her and trying to impress her.

What a fatal mistake… I STILL don't even finish papers on time or study as much as I should for tests, and my grades are STILL getting WORSEEEEEEEE!!!! I'm hopeless!! I've tried and tried and tried and tried to bring my grades up, but nothing ever works. I'm still that same procrastinator, that same slacker!

I wish someone just understood me… I feel like everyone just doesn't even give a damn. They should know that I'm suffering from something, and that's what's causing me to do so poorly in school – my teachers send me ******* interims NON STOP. and it's really weighing down on my soul. I've never really had many friends, so I can't really talk to anyone (as if that would help anyway)…

I really don't like humans. Humans are just big globs of flesh filled with internal organs, blood, bone, brains, intestines, and other disgusting stuff. Now when I look at a person, I imagine what they would look like if I just saw them one layer under the skin. They would look sick and disgusting. Yet we call that "beauty." Think of what love is, too. It's a bunch of chemicals and electric signals in your brain just making your body respond in a certain way because of someone's behavior or appearance. **** love. Love is ****. And also, we've completely lost ourselves on this ******* planet. Look at all the wars we've waged, the billions humanity has killed in all of time, our irresponsible behavior on this planet and the effects it's having (global warming), our fascination with the world itself instead of something more important like God and the hereafter. Look what we've done. We've made a fool of ourselves. **** life. Humanity is morbid.

So basically, I think I'm really a mix between anger and sadness. Right now i feel angry for what we've done and what has happened to myself and others, but at the same time i feel sad, for what we've done and what has happened to myself and others…. strange indeed. my heart feels heavy right now.

All I can do is remember those days when things were great, when I was getting straight As in school, when the world was a better place. I've often considered doing some violent things in my school, like Columbine but without the killing (I don't believe in murder). But I do feel like getting a bit of revenge on that stupid girl I liked.. She's the one who made me like her in the first place, so why not return the favor and **** up her life? But right now, all I want to do is not be here. Anymore. Just poof out of existence, or maybe run away. I'm so lost.. I'm barely here. I wish i could explain myself but words escape me. It's too late to save me. It's too late.

This world's an ugly place. There's nothing beautiful.