I think you were trying too hard to be mysterious and secretive and ended up with a convoluted sentence full of pleonasm. Blackmailers are always more evil than anyone else in the film; if you know someone's secret you have the keys to the secret; you can't blackmail a homeless person with homelessness.
Maybe you wanted something like one of the following:
A fifty year-old man blackmails a twenty year-old woman, leaving her the choice between living with him? as his mistress or unemployment and homelessness.
A middle-aged man tells a homeless, eighteen year-old runaway he'll inform her parents of her whereabouts unless she? agrees to live? with him as his mistress.