The 41-year-old director of Stewart's film, "Snow White and the Huntsman," also issued a statement on Wednesday saying he was "utterly distraught" over the pain he has caused to his wife and children following his indiscretion with the 22-year-old actress that made headlines around the world.
"I'm deeply sorry for the hurt and embarrassment I've caused to those close to me and everyone this has affected. This momentary indiscretion has jeopardized the most important thing in my life, the person I love and respect the most, Rob. I love him, I love him, I'm so sorry," Stewart said in a statement to People magazine.
A fling between a Hollywood star and her director is nothing new in showbiz, but this one gained widespread attention because of the high-profile people involved. Stewart, 22, and Pattinson, 26, portray the vampire-human couple of the "Twilight" series of blockbuster romance movies who are deeply in love in the films.
The pair's on-screen romance transferred to their real lives, and they confirmed they were dating in 2010. But they have tried to remain discreet in public and don't often discuss their relationship.
Given their past, Stewart's romantic liaisons with director Sanders, which was reported with photos on celebrity news outlets including People and Us Weekly, surprised celebrity watchers and put the trio in a publicly awkward situation.
"I am utterly distraught about the pain I have caused my family. My beautiful wife and heavenly children are all I have in this world. I love them with all my heart. I am praying that we can get through this together," Sanders said in a statement to Reuters.
British director Sanders is married to model and actress Liberty Ross, 33, with whom he has two children. In a twist befitting of a good Hollywood drama, Ross portrayed the mother to Stewart's Snow White in the "Huntsman" tale.
Representatives for Stewart and Pattinson did not respond to Reuters' request for comment.
Most recently, Pattinson and Stewart were together promoting the upcoming final "Twilight" film, "Breaking Dawn - Part 2," at San Diego's Comic-Con earlier this month.
Universal Pictures announced in June that they were moving forward with a sequel to "Snow White and the Huntsman," but did not confirm whether Sanders would helm the film. Stewart is expected to reprise her role, but is not confirmed.
