Read the full text of Richard III Act 3 Scene 3 with a side-by-side translation HERE.
The queen's brother Earl Rivers, her son Lord Gray, and their friend Sir Thomas Vaughn face their executions at Pomfret.
Rivers declares they're all dying for their duty, and Vaughn declares that all who live after this will regret it.
Gray notes that their execution seems to fulfill the old Queen Margaret's curse. She had railed against them for standing by and watching Richard murder her child.
Rivers points out that Margaret's curse wasn't only directed at them; Richard, Hastings, and Buckingham were also included. (Actually, Gray and Buckingham weren't included in Margaret's curses, and Buckingham was only warned.)
Rivers calls out to God in the hopes that Richard, Hastings, and Buckingham will also receive their parts of the curse. Rivers also prays that his and his colleagues' wrongly spilled blood will somehow spare his sister, Queen Elizabeth, and her children.