I want to get out, am i being selfish?

My brother has shown symptoms of asperger syndrome and traits of OCD since he was about three. My mum suffers from paranoia and my dad spends most of his time away or at work. I live in a small village and have few friends which I don't think is a problem but when I want to escape there's usually no one around and I end up taking a dog for a walk by myself which just means I have far too much time to think and then I end up getting angry or upset. The only people who live in my village of my age went to my high school and I know most of them are superficial and bitchy and the ones who aren't keep to themselves.

I'm not shy, I'd happily talk to anyone if they started a conversation with me but most of these conversations lead to nowhere and once they leave I end up lonely once again. I don't like to lay down problems on my friends because it tends to make the conversation awkward and when I do tell them, nothing is solved and it ends up that I've just brudened someone else with my problems for nothing.

In truth I've known for a long time that what I need is to get away and I should be off to university next year. However, I feel bad about leaving my family alone because there have been cases in the past when things have gone awry and I've had to support my dad through it or be there for my mum or brother and I don't know what will happen if I leave but I just can't take things anymore. I could take a year out and see if things get better because my brother's on a course to help him manage his OCD and more recently, anorexia which should be finnished sometime in March next year but the course is hard to get through and there's strain on the whole family. However, if I take a year out and do nothing then it'll affect my university application and I won't have the support of my college.

Am I being selfish by leaving this year?