Season 3 of the Netflix hit The Crown will introduce Camilla Parker Bowles, producer Suzanne Mackie recently revealed. That’s exciting for fans of romantic drama and palace intrigue, but it’s terrifying to Camilla’s husband, Prince Charles. “Charles is having sleepless nights over it,” an insider says. “He can’t seem to escape his past and is feeling anxious about what The Crown will divulge.” Charles, 69, and Camilla, 70, first dated when they were in their 20s, and their affair years later while Charles was married to Princess Diana turned into a massive scandal that many in the U.K. haven’t forgotten — or forgiven. “The next season of The Crown will reveal what went on behind closed doors with Camilla and Charles, and in his turbulent marriage to Diana,” the insider…