I'm feeling a little stressed, help please?

Every healthy life has its share of stress I know; for me I feel like it's never ending. Literally every moment of my life I live in anxiety, even when everything seems to be all right. I've just recently started having panic attacks and I've never told anyone. I am in 11th grade and, on top of keeping my grades up which stresses me even more, I have to think about college. I have no idea what I want to do, where i want to go, and am feeling freaking terrified about SATs, from what I'm being told this test is basically determining my life, and I don't even know how to study for them. I also just found out that the man (mom's ex boyfriend) who I was counting on to pay for at least some of my college tuition is no longer with my mom and they will probably never get back together, so i have no idea how i'm going to pay for college especially with these new budget cuts. I have a feeling that, if i ever become successful, my parents plan to mooch off of me as much as possible in their later years, I feel like a meal ticket. On top of educational issues, I have more personal ones to. I suffer from low self esteem, and generally find it difficult to find things about myself that I like and that I can tell others about. I have also pretty much forced most of my friends away, admittedly some of it was my fault but I can't help but feel it's not all mine even though they respond with the sterotypical "it's you, not us" answer. How do they expect me to act when they never invite me to anything or talk to me and when I confront them about it they act rudely? Am I supposed to be grateful? I also have another group of friends that I'm pretty sure keep me around for the purpose of mocking me non stop, so that makes me mad. I have started to have images in my head of me killing people I don't like or people who have disrespected me, as well as images of self mutilation. When I see someone that seems to be doing something better than me or is more talented than I am (thanks to my low self esteem) I have the urge to kill them to. I have considered suicide, but I've only ever cut myself with a razor and I wasn't even trying to kill myself, I don't know why I did it; that made me feel pretty pathetic. Should I get help? And if so, can I do it discreetly? I know if i say that i need help that I will be considered crazy by my family and friends, I feel like they hate me anyway though so i guess it doesn't matter. I generally just feel pretty lost, I don't really know who I am, I just know that I hate myself...