Jess is right. This bandit is heading into Santa Fe, not really expecting to make it out alive. With this thought in mind, he's looking back on his life, thinking of all the "hearts I broke and the lives I took". He's thinking of how he went wrong in his life, that he did the things he's done and how he's ended up here. He knows that he "ain't getting into heaven", but he also knows that he's got to do what he's got to do, regardless of outcome. It is truly a beautiful and touching song that is so well-written! It takes a deeper look into the heart of a criminal and humanizes him in the process. It finds me feeling badly for this bandit but also realising that everyone must eventually pay for the things they've done, or as Jon puts it "every dog will have his day" even if it is the world that made him evil.

If you have any questions about any specific lines, let me know, and for whatever it's worth, I'll give you my interpretation on them.