Green’s Dictionary of Slang

1. (US black) an ex-lover.

1923		Ethel Waters ‘You Can’t Do What My Last Man Did’ 🎵 Why you can’t love me sufficiently, / To make me forget my used-to-be.
1930		‘Freight Train Blues’ in Botkin Folk-Say 334: It took my good man, come back an’ got my used-to-be.
1941		Leadbelly ‘Roberta’ 🎵 Lord I thought I spied my old time used to be / [...] / And it was not nothing honey, but a cypress tree.
1956		Charlie Feathers ‘I Can’t Hardly Stand It’ 🎵 You’re just out with your used-to-be, / I can’t hardly stand it, you’re troublin’ me.
1958		(sung in 1941) Book of Negro Folklore 387: I got something on my mind [...] It’s just my old-time used-to-be.

2. attrib. use of sense 1.

1966

B. Jackson Get Your Ass in the Water (1974) 136: Maybe three or four of your old used-to-be broads tell you, ‘Daddy, I’ll go your bail.’.