Hello, lorna. A caregiver doe not abnegate the right to her/his own life. Are there other siblings that could and should help? Can your parents afford to pay for some help to come in so you can take some time off for yourself?
Medicare may have some help:
http://www.medicare.gov/caregivers/
http://helpguide.org/elder/caring_for_caregivers.htm
http://www.caregiver.com/articles/pr..._to_say-no.htm
http://www.strengthforcaring.com/man...s-a-caregiver/
http://psychcentral.com/stress/
NAMI NH has an online guidebook (108 pages):
Guidebook for Older Adults (PDF File)
Please take care of yourself too.