To be honest, I'm in a similar situation, and I understand how difficult it is to be torn apart by what he says, and the lies that follow. It's hard to take in that he's with someone else, when it feels like you put in so much just to get smacked constantly in the face with all these lies. I'm still there dealing with it, so I do know how you feel. I understand how hard it is to not talk to him, because I cave in every time. He says he loves me, and I know it's bull****, but I want to believe it. Like, if he loved you he'd be with you and drop the chick. But, knowing that's not the case, he doesn't really love you like he claims he does and you need to move on from him. You'll surely do better. Like you said yourself, you're a sensible girl, you'll find someone else who'll treat you right and this guy'll just be a memory. A bad one, at that.
Hope this helped. ;p