Hiding isn't going to help, even though it feels like the best option. Ignoring things won't make them go away.
Firstly, sort out your school work, go and see your head of year or your headmaster and tell them how stressed you are. They are there to help and to get you through your A-levels. Your Spanish teacher is being imcompatent (sp) and should be picked up on her beahaviour.
You might be able to arrange different deadlines with your teachers if they know what stress you're under at home looking after your dad. I understand the Cambridge applications are pressing but spend some time making a start on your History coursework if it's at all possible. As for your Economics, your group should pull their weight, so again, have a word and don't do the entire project yourself.