Javert's arc from infiltrating the barricade to his suicide brings home how criminally misused he's been by his superiors. He's a terrible spy, too honest and rigid for the role, and yet his honesty and rigidity depend to a degree on his not interacting with criminals as normal people outside of the system, as spying requires him to do. So what do they do with a pretty competent cop? Put him in a situation which undercuts his strengths, nearly gets him shot, and then leads to his suicide.
The disordered list of observations is more affecting than an actual suicide note. Number three and number five on the list...ouch. Is he trying to protect Mme. Henry, partly at least, from an experience like his?
But how to manage to send in his resignation to God?
echoing his attempts to offer his resignation to Valjean earlier. Which goes with Javert's feeling God as "this new chief" and "this other superior." (Also reminds me of Ivan's phrase in The Brothers Karamazov about "returning one's ticket" to God. Dostoevsky liked
Les Misérables a lot and, interestingly, reread it while spending two days in jail.)
Here day embraces night, and says: I will die with you and you will be reborn with me. From the heavy embrace of all desolations springs faith.
The real name of devotion is disinterestedness.