Captured killer David Sweat gave cops a blow-by-blow of his escape and time on the run with fellow fugitive Richard Matt — revealing that their original plan was to flee to Mexico with the help of Shaw-skank prison worker Joyce “Tillie” Mitchell. Sweat claimed the lovestruck sewing-shop supervisor, who is charged with smuggling tools to the convicted killers, was the only other person who knew of their elaborate breakout plan, sources said on Monday. Sweat — who a source said was “spilling his guts” to investigators — said he and Matt planned to drive to Mexico in Mitchell’s car following...