You try to please them because you want to do what's right, not what's fair. I respect you for that, and so should you. Impressive is the person who will continue helping others when he or she gets nothing in return. If you feel taken advantage of, you can still find solace in the fact that you're doing the right thing, and at the end of the day, you get to fall asleep with that knowledge. If the people for whom you are working are no longer around, it's worth considering that you might be doing what they wanted, but not because they wanted it.
I'm guessing a lot here, because there aren't many details to work with, but something tells me that if you thought it were the wrong thing to do, you could stop. But don't stop doing the right thing because you started with for the wrong reasons. I buy Girl Scout cookies for the taste, not the charity, but they don't mind.
Good luck, man. Hope you feel better tomorrow.