Absent From Felicity — Richard Quarry

Twenty-eight years ago the black hole at the center of our galaxy spasmed outward to swallow the space habitat Tycho Brahe. Now John Gottschalk, sole survivor of a would-be rescue mission, searches the banged-up torus for survivors. His chances? Somewhere between null and void.
Only not quite null enough. For instead of the grateful Robinson Crusoe Terrans he hopes to find, John falls into the hands of Ophelian mercenaries. The biggest, nastiest, most dedicatedly sociopathic soldiers in the galaxy. And the Terrans? Slaves, one and all.
John better get word back to Earth to send in the Seventh Cavalry. Soon as he stops serving as ping-pong ball for Ophelians acting out their utopian blueprint, “Survival of the Screwingest.”
Chock full with high adventure, genetic derring-do, and some of the most exuberantly blood-thirsty characters ever to bring a galaxy to the brink of destruction, Absent From Felicity launches you on a tour through the wilder frontiers of space.