LGBT i want to come out but cant?

im 17 and ive known im gay for about 2 years now but im in a really difficult position, i dont want to come out because it would meen admitting it and im hugely ashamed of what i am, dont get me wrong im in no way homephobic but i hate my self for who i am, i meen ofcs im scared of the fact my friends and family would leave but im more scared of admitting it to my self, at least when i dont tell anyone its only me that has to suffer with the srong front, i hate lying to my friends and i really want to tell them but the thought scares me so much and i just dont know what to do, its been getting me steadily more depressed for the last two years and sometimes i just wish it would end but know i wont, im just scared and dont know what to do