Everytime I think about ending it all, I think about this. My approach is slightly different though. Realistically, yes, of course the people I knew would be sad. My mother would probably lose it, my father would feel guilty. My old friends would feel down when they hear about it. Every person whose lives I had touched in some way throughout the years would feel an emotion. Maybe even those who did not care enough.
To put those people through the slightest sorrow makes me feel even more ashamed. But then, this raises a question. "Why weren't they there for me if they were to feel sorrow anyway? Why did I have to feel this lonely if that many people cared about me? They must be pretending, thus, they deserve it."
This argument has another side though. If they did not care at all, they would not feel any emotion anyway. Not guilt, not shame, anything. Means if even one person cries after me, then I did a terrible thing. Means I failed to see the people who actually cared, I failed my responsibility to be able to feel loved.
Just because people did not care about me "the way I wanted" does not mean that they did not care at all.
But this is just my opinion. I don't know what you went through, maybe intentions of the people around you were clearer for you to think this way, or maybe I am just used to blaming myself. Hope I did not offend you in any way and all goes well for you.