Guilt, How are some exempt?

I have such guilt over things undone. My head knows that I did all that I could but my heart feels that there must have been more. There are always times in our life that we don't have as much time to spend with family as we would like, that is part of life. It is not something that anyone could ever hold against us, as long as we try. When she needed someone, we were there, without question. Yet it seems there should have been more that we could do; what I do not know. So where do the people who did not try ever begin to deal with that? Luckily I can never know myself, I can only wonder and imagine. More than that though, how do you portray to people that you tried when inside you know that you didn't? How do you down the people who did help your mother on her death bed? Why would you turn on the people who nursed her in her last hours? I continue to be amazed at the things that people are capable of, the things that they can convince themselves are reasonable and the things that they will do to get what they want. I hold out hope that at some point they will have to pay for the things that they have done but for now all that I see is that they are just thrilled to "have their lives back". I am convinced that with the way this world works I will be alone on my death bed while they will be surrounded by people that they would never have been there for, if their circumstances were reversed. I must live with myself and only myself though; I do not look forward to rewards in this life but peace that surpasses all understanding and the reward of life everlasting.