I can't help but wonder if my father truly hates me, the way he treats me is deplorable.
My father belittles me and my feelings, he doesn't support me on anything I do, I tell him I'm thinking of being an interior designer he goes off and tell me
"You might as well drop out of high school, because all you need is a warm body and half a brain"
Then he tries to push becoming a doctor, lawyer, or sell insurance, and puts me down for wanting to choose a career in art.
He says I'm nothing but a wimp, because I try to respect him as much as resent myself for doing it, and says I'm nothing and I'm full of it.
He was also abusive, when he was fighting with my mother I grabbed him and he slapped me so hard it left an imprint, and one time before that he threw me across the room
(I was 11).
He constantly makes promises, says he'll send child support, and blows it off.
When I was suicidal and depressed after my grandfather who was more of a father to me died, he goes of and tells me to do it, and he won't miss me.
He encouraged me to do it, he said he'd even buy me a gun to do it.

Other times he plays the act of the loving and supportive father, he acts like a human being, and then the next day he goes back to the way he was.
Whenever I try to tell him how he makes me feel, he turns it around on me, makes me feel bad, by saying I'm the reason he treats me this way.
My mother is unemployed, but within the next month she should have disability and get a settlement from an accident she was, and my inheritance will be available so I will no longer be financially troubled, so I won't have to ask him, which is the only reason why I speak with him.
I've started to hate him, I know it's wrong to hate others but I can't help it, when my birthday comes around I'm going to tell him to in these exact words "Kick rocks, eat , die, and rot in hell.

I'm almost eighteen and even now I can't seem to understand why he hates me, I mean, you wouldn't treat someone you care about like this.
What could I have to warrant such treatment? Or is he just being a scumbag?
I feel wrong for hating him, what can I do?

As you have figured out, it's him, not you. I don't know what he has experienced in life that would cause his attitudes and behavior. Probably as a kid, he was treated just like he is treating you now. I know it will be hard to think this way, but don't hate him. Instead, feel sorry for him. If he would allow us into his heart, I'll bet we'd be shocked what we'd find out.

Well, now, here's a question to which I can relate! And I agree completely with Wondergirl. It's not you. Each of us lives in a bubble. In psychology, we call that "sphere of reality". It's determined by our past experiences and how we relate to the world, and no one can ever truly enter someone else's sphere. You may never be able to see the world through your father's eyes, but that doesn't mean you have to feel bad when he belittles you.

There's another psychological construct that's called "self-talk". If he belittles you, it doesn't mean anything unless you add to his verbal comments your own mental comments. "He says I'm dumb, so I MUST BE DUMB." Try to catch yourself doing that. It's doubly hard with a parent because we all want our parents' love and approval, but he's just a guy. Just a guy. And he's a guy with his own issues. Love yourself and know that you're doing the best you can do. If you're not, then give the Best You a try and you'll find peace in the knowledge that you're a good person no matter what he says or does.

Good luck! It took me decades to get past this problem in my own life. I hope you're a faster learner than I was.