The teenager wowed the judges and audience on Saturday night's opening show with a cover of Adele's Make You Feel My Love, and he said today the emotion came from thinking about his ex.
Sam explained: "I am currently single, my last girlfriend cheated on me. She is not a very nice person actually, so it is probably a good thing.
"It is quite a while ago but the keen sting of that still hasn't gone away."
After his performance at the weekend, new judge David Walliams raved: "I think when you tackle a song like that, it's not just your voice — it's the way you make us believe you've lived every line of that song. I was completely blown away."
David and all o f the panel - including returning Simon Cowell - gave Sam a yes, which he was over the moon with.
Sam added: "It was great getting his opinion though and he seemed to really like it."
Britain's Got Talent 2012 continues this Saturday on ITV1.