Green’s Dictionary of Slang

(US) one’s self.

1845		W.T. Porter Big Bear of Arkansas (1847) 135: I raised my arm, trimblin’ like a leaf, and says I, ‘Jem! – I’ll have your melt!’.
1858		in G.W. Harris High Times 134: Why, durn my melt ef the passon’s sister didn’t have his haslet outen him.
2021		L. McInerney Rules of Revelation 146: ‘What if I’d gotten up out of bed the night my mam died? [...] What if I’d taken the bottle off her? Don’t go there, you’ll only break your own melt’.