LOS ANGELES - Kristen Stewart has apologized publically to "Twilight" co-star Robert Pattinson following tabloid reports she had a brief but steamy affair with her "Snow White and the Huntsman" director Rupert Sanders.

The 22-year-old actress issued her apology to People Magazine on Wednesday. It was quickly followed by an apology to People from the 41-year-old Sanders to his family. Stewart has been in a relationship for several years with Pattinson. Sanders is married and has two children.

Stewart said her "momentary indiscretion has jeopardized the most important thing in my life, the person I love and respect the most, Rob." Sanders said he is "utterly distraught about the pain I have caused my family."

Us Weekly published photographic evidence of the affair in their latest issue, with the two in steamy and compromising embraces.