A violent criminal who gunned down a Dedham painter after winning a pardon from former Gov. Michael Dukakis is up for parole again, reopening old wounds for the man’s grief-stricken widow. “It still hurts,” said Nadine Efstathiou, whose 29-year-old husband, Kostas, was murdered in 1983 by Thomas Childs. “My kids are upset about it too. They grew up with no father and it was a tough road for me to bring up three kids by myself. Thank God my family was there to help.” Childs, who was convicted of second-degree murder for fatally shooting Efstathiou in a Roslindale Dunkin’ Donuts...