I know that when I am at my lowest I believe and I mean truly believe that everyone including my family would be better off without me. This only happens when I am very very low, so I am assuming that is where you are at the moment and if that is the case I urge you to get in contact with your Dr or at the very least phone a support line.
Trust me your feelings are wrong your family need you very very much. I have been where you are and have come through it to the other side so know this to be true.