When one is depressed, often the only thing that will not enrage you is total agreement that everything is terrible and there's no brighter side to be found. But someone on LW's situation (recent cancer survivor, caregiver of several small children) whose sanity might depend on convincing herself IT'S ALL WORTH IT AND REWARDING, might not be the ideal option to vent. Both would be better off if sister sticks to professional advise, and LW refrains from advising at all.