I get exactly what you are saying, but I think he is going further than just moving on in life... More into taking his own life.
Take the line "Cos it's all in the hands of a bitter, bitter man", I think this is in relation to god in many ways, certainly to the Christian god, looking down on his people who have left him and have turned to the path of the christian devil Also, from a down and out perspective, god could look like an extremely bitter old man fairly easily...
Furthermore, the lines "So I smiled and tried to mean it, To let myself let go" could mean letting yourself go from this world, leaving the mortal coil. I think this is furthered by the lines in the first section "In any other world, You could tell the difference, And let it all unfurl, Into broken ruminants", possibly referring to the blood from wrists unfurling in the water of a bath.
The finality of this piece is definitely in the "say goodbye to the world you thought you lived in", which to me means that the person is saying their final goodbyes to the world that they used to think that they fitted into, with the references of "take a bow" possibly meaning that everything that this person has done in their life has been an act, cemented by the line "play your part".
The constant reference to the smile is, I think, a final part of playing the character, trying to show that while you have had enough of the acting and the playing of the part, of the depression from being "a lonely, lonely heart" that the world has not won, and that in the end, you were smiling.
Or maybe I'm on something... Well, we sure as hell know its not prozac!
ttfn,
badspyro
