Trust me, Ive had a rough life myself, the thought never crossed my mind.
Be glad it hasn't.
It doesn't matter what went through her head, when someone says, "They would be better off without me," that is a feel sorry for yourself move. Only encourages suicide even further. No one would be better off if you killed yourself. Its the stupidest thing I have ever heard honestly. When people are depressed they do not think rationally, and tend to think selfish and irresponsible thoughts. That is my point.
Still don't get it, because I have never wanted to kill myself. There are people in life who are well worse off than most of the suicide cases that happen here in the United States. It is funny how we as a society have used suicide as a way out, when a child or adult in Africa who is starving to death, would rather starve to death, than kill themselves.
It's as you said, a mindset. However, the rest of your post clearly shows you do not understand what said mindset entails. It is not simply thinking that the world would be better off without you, it's thinking that you no longer want to continue living. Which is vastly different.
People starving to death and fighting to live want to live. People depressed to the point of suicide to not want to live. They would rather everything just stop. It's not about being weak or strong either, so don't give me that crap. If you've never felt that way, you have no right to judge what others choose.
Should they have killed themselves? Almost certainly not. Would things have gotten better eventually? Most likely. Did they hurt others around them by taking their own life? Yes. Were they weak for killing themselves? Not at all.
If you have no idea what it is like to seriously consider killing oneself, please don't argue with this. Would you have the courage to jump off a cliff, or pull the trigger to the gun, or overdose on medication? Do you know exactly how much thought they put into it beforehand? It's not something that's done on a whim.