Drama begets drama. You need to just be straight up, and tell him that you know that he's been keeping a long-distance girlfriend a secret from you. There is no such thing as an "off again, on again" relationship. There are just two people who are into each other and either he is up in her guts or not.

This guy and this woman either need to stay committed to each other, or figure out how to live without one another. And you have to stop being the bologna in this tacky ass sandwich.

Just be up front. Matter of fact. Dispassionate, even. Tell him it's kind of unfair that you had to find out behind his back that he has been running around with an old flame. Don't get mad, and try to fight off the tears. Let him know that you want to stop seeing him. You're both going to be happier if this happens. He could resist. It's hard to give up having it all. But his having it all is at your expense. You're no back-up girlfriend.

It's basic common, moral sense. He knows his days with you have been numbered. Oh well. He knows he's in for a drubbing. You asked him "to talk." He's sweating ball bearings. You're either preggers, or have a mobster husband who just got out of the joint, or... he's been found out. Surprise him by being more mature than him. This will leave him utterly baffled. After you've told him that you're moving on, wish him well. Then disappear in a puff of smoke, like a ninja. Poof!

Are you hurt? Do you feel wronged? Angry? I totally understand. Go for a jog. Bitch to a friend. But, personally, I hate drama. A clean, fast, emotionless getaway is the fastest route between this breakup and a happier you.