It sounds like you're suffering from depression mate. I think you really ought to go to the doctors and see if you can get any counselling or antidepressants, or failing that just have a chat to the Samaritans - talking through how you feel sometimes can take a weight off your shoulders.
I think it would be a really good idea to leave your hometown to go to uni - and uni's really something to look forward to. Regardless of where you go, or what you want to study, there's going to be hundreds of people and societies where you can be yourself and have fun. Do you think you could possibly be bored by your surroundings and school life? I got really frustrated with having to go to school in year 13 - most of my friends were in the year above and on gap years/at uni already and I felt like I'd already outgrown it. I know life can seem really boring and dull sometimes, but try to concentrate on the positives rather than the negatives - if you stare at your muddy feet whilst walking through a field, how can you look up and see the sun shining above? And trust me, your friends and relatives WILL definitely care if you weren't there. In fact, they would be devastated.
I hope you feel better soon. xx