How can i stop being so depressed about my family?

I'm 15 and about 4years ago my mum got a disease where she lost most of her vision over a period of time. Shes has now lost her vision about 2months ago. My dad about 3years ago got something in his stomach, they said it was ulsurs but they didnt know...

what it was. He was in pain a lot and he couldnt do anything but rest. he insited on going into work which made him even worse. This left him with very bad scars after they had gone. He is still resting all day but is now off work due to depression and is even more stressed because he cant go in. I cant go out because I have to look after my dad. my mum gets her friends to give me a life to the shops to get food and drink. This is still going on and I dont know when it will get better. How can I stop feeling so depressed?! I really dont want to go on anymore.

That is a heavy burden for a 15 year old... but, it seems that you have risen to the challange... and I admire you for that.. however, it is very understandable that you want a life outside of the care giving... and this is ok... it is quiet normal... and you should not have to feel ashamed of feeling this...
Is there no one else that can assume some responsibility for your parents? Are there parents still living? Do you have any relatives that would offer to help?? What about a church group, do you belong to any church, or could you , that would be a help? What about social services, they usually know of resources that are available, to help, if you can't find their number, you can call the food stamp office, they are usually in the same building.
Asking for time off, is an option... just an evening away, once a week... would be a help.. it would give you relief and a different perspective... and if you believe in prayer, here are some links where you can post prayer requests... godswork.org, wjcr.org, dailyguidepost.org, needhim.org Blessings...