Fear of Failure

I am an 18 yr old girl.I couldn't pass out of my 10 and 11 class so I had to repeat them.I am very depressed for not being able to succeed and even now that I have written my 11th class exams again I am sure I will fail in them.I am terrified of failure.Though I am not a bad student at all;I get very unwell before my exams due to the fear and tension of exams. Every time there is an exam I used to get severe cough and Asthma attack.But now along with some cough I get headaches.Even now whenever I think about my horrible exams I get a headache.Not only exams whether it is any important decision that I have to make or almost anything that I have to do I get tense very easily.I am always thinking negative about every thing and situation.I am terrified that I would make a wrong decision or I would not live up to my and other people's expectations.Even simple things like choosing a dress takes me a lot of time to decide.I take a lot of time to do things, I feel I am very slow at learning and doing things which girls my age can do quiet easily.I am also depressed about my looks;I am extremely short(4.9 inches tall) I am fat,weak,have pimples and dark circles,have dandruff and split ends.Overall I am extremely unhappy with myself.I want to hurt myself(as a punishment for being so bad).I think about committing suicide but I know I will never do that.But I really want to run away from home I don't want to hurt my family for the mistakes that I do;I don't want to trouble them.I also think that I run away from problems(mostly I just make myself sleep whenever I have a problem).I think I cannot do things in time and get paralyzed by fear that I cannot do it at all.And I leave all hope completely.I am mostly extremely sad or extremely happy.I don't have many friends I don't talk with people much;but I am a chatter box at home.I am also very shy.I fail to judge things correctly I do not know how to react to things correctly.My family tells me not to take any tension and then you can do the work effectively;but I don't know how to not become tense my body immediately starts reacting to tension.I also have difficulty in communicating with people.I think people hate me and don;t love me at all I crave for some love and appreciation.I also don't know how to talk to children I don't like them because they are so truthful they tell me on my face that I am fat and ugly and short.I don't like the food my mother prepares at all so I don't eat for long time and when I eat, I eat very little food or some other junk food(mostly fried).I am becoming very angry,irritated,depressed,impatient and I am losing interest in everything.I haven't had a pleasant time since I was 12 with the start of my menses.From then onwards I became unwell continuously with weakness,severe cough and Asthma.So I did not have good education at that time.I don't remember anything of my years from 12 to 16 except being unwell and unhappy. I have extremely low self esteem.I truly hate myself.But I know it's a wrong thing to do.I don't know what to do.Please help.