Lady Gaga has defended Kristen Stewart's cheating.

The 22-year-old actress has publicly apologised to her boyfriend of four years Robert Pattinson after she was caught in a steamy make-out session with her 'Snow White And The Huntsman' director Rupert Sanders and Lady Gaga has weighed in , telling people to leave them alone.

She tweeted: "Geez this kirstew rob stuff is brutal. Makes me sad the way press acts. Hope they're ok (sic)."

Kristen's statement today (25.07.12) read: "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 jeopardised 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."

Sources close to the actress insist she wasn't having an affair with Rupert and it was a fleeting mistake.

An insider said: "Kristen is absolutely devastated. It was a mistake and a complete lapse in judgment."

Kristen and Robert, 26, have been dating since meeting on the set of 'Twilight' four years ago, in which they play vampire Edward Cullen and his love interest Bella Swan.