Madness or Martyrdom?

"And now, my lord, since we are in forever,
This work was ours, which else might have been slipped;
And, if we list, we could have nobles clipped
And go for less than beggars; but we hate
To bleed so cowardly. We have enough, i'faith:
We're well, our mother turned, our sister true;
We die after a nest of dukes. Adieu."
(V.iii.140-146)

It is interesting that Vindice confessed to his (and Hippolito's) murder of the duke to Antonio so quickly. Perhaps his initial belief was that Antonio would applaud them since they, in a way, did avenge his wife's rape? However, Antonio quickly turned on them and ordered their execution, claiming that he was the same age as the duke and if they killed him (the duke), they could also kill him (Antonio) just as quick (V.iii.124-125). Although Vindice questions Antonio's order of their execution at first, he does not fight it or deny it later and instead seems proud of what he has done. Afterall, according to him, his family was better off now than they would have been had things remained the same and these crimes not been committed (V.iii.145). He accepted his execution without resistance, and I wonder if this was his intention all along. Was his only purpose for telling Antonio in search of a reward, or did he tell him as a form of liberation and a "my work here is done" kind of thought, so he no longer found a purpose in living since he got the revenge that he wanted and his mother/sister were now better off? Yes, the whole skull thing was a bit on the madness side, but right now, I think Spurio was the most sane of them all since he was pretty much the only one who got exactly what he wanted in the end. Not to mention that he managed to outwit/outlive the "nest of dukes." Also, his (and Hippolito's) deeds now left Antonio, the man they considered the most honest and suitable for the position, in power. Perhaps this ending was not so tragic, or at the very least, it has been the least tragic ending of the plays we have read so far.