Years ago a therapist recommended a book on setting boundries to me that was very helpful. One technique I found very helpful at work when my boss would give me a week's worth of work that he wanted done by the end of the day was to go to him and say 'I can't get this all done in the time frame you established. Please prioritize the work, and I'll get started on it.' It was amazingly effective in me not being forced to take on the weight of the world so to speak.

Prioritize what absolutely has to be done, and go from there. No one can do everything without ending up burned out. Stand up for yourself, and believe it or not, your family will respect you more. The times I've stood up for myself have usually resulted in being treated better as the people I'm working with find out I won't tolerate not being respected.