Natalie Portman is ready to turn the page on her marriage to Benjamin Millepied. According to insiders, the Black Swan star, 42, has been eager to divorce her longtime spouse, 46, after his shocking affair with a young activist was revealed. “Natalie is officially pulling the plug on her marriage,” a source claimed of Portman, who married the ballet performer in 2011. “She really tried forgiving Benjamin — the last thing she imagined in her life was a divorce — but she could not get past the betrayal. Natalie finally decided that she couldn’t be married to Benjamin anymore.” “They went to coun…