We were shocked when reports surfaced this morning that Kristen Stewart cheated on longtime love Rob Pattinson with her married Snow White and the Huntsman director Rupert Sanders, and we were even more stunned with both the starlet and Sanders released statements apologizing for their affair.

Photographers caught Stewart and Sanders kissing in Los Angeles on July 17, and a source tells Us Magazine that they "couldn't get enough" of each other. The two were first introduced in 2011 when production on the action flick began in England, but a source tells E! News that they were NOT hooking up when they shot the movie. "I can guarantee you 100 percent that nothing happened when they were working -- nothing!" the insider says.

Stewart told People magazine, "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."

Sanders added said in his statement, "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."

Stewart has been in a relationship with her Twilight co-star for nearly four years, and Sanders has two young children with his wife, actress/model Liberty Ross. Though there have been reports that Pattinson has stepped out on Stewart, this is the first time that there has been any hard evidence of infidelity in their relationship. We're guessing Pattinson found out about this around the same time as Sanders' wife, seeing as he was all smiles on Sunday when he accompanied Stewart to the 2012 Teen Choice Awards.

Neither Pattinson nor Ross has issued a comment, but before deleting her Twitter account, Ross tweeted, "sometimes bad things fall apart so better things can fall together," along with a photo below of a drunken Snow White, with the caption, "Not so pretty or so pure after all."