i was like you i stressed so much...infact i still do stress a bit...but i find a VERY helpful way of destressing is exercise. I go running 3 times a week and do other activites in between. It will help get your mind off things and plus it means more oxygen will get to your brain making you think alot more quicker. Also stress can be linked to diet. IF you eat alot of fruit and veg it'll keep you more alert and help you to handle things better in turn leading to less stress
I try and listen to music it sort of takes me away every now and again. Do something you enjoy; sometimes i go out with a few friends and we play some sports, that takes my mind of work etc for awhile.
Although it sounds as though i feel the same way as you do........incredibly stressed. But hey we're all stressed some more than others.
Make sure you give yourself time out to relax as well- don't try to spend every waking moment revising because it'll just make you more stressed and tired and probably be counter-productive. Give yourself breaks after each revision session where you can watch your favourite TV programme or do something else you enjoy, and every so often give yourself a day off to go out with friends or just chill.
listen to magic fm late at night when there are hardly any adverts also just think of exams and revisionas something that must be done, will be over quickly and then the fun begins!