I'm not gonna judge you on cheating, since frankly I know what it's like to get into bad situations... Am I the only one who sees that this guy needs advice, not a slap on the wrist? It seems like he's a bad guy for cheating on someone, but the heat of the moment does things you regret, and everyone has good intentions that don't work out - which I suspect to have caused a lot of these problems. I will admit, this goes beyond mistake and into monumental cock-up, but he didn't ask to be judged. He asked for help to fix the situation.
You're really going to have to break it off with one of them. When you look at them, which do you think you could see yourself living with? Which do you think you would never tire of? It appears you did tire of your ex, since you cheated on him. And again, you cheated on the handsome guy meaning that you must have got tired of him too.
I accept you probably care for all of them, but you need to consider the fact that if you care for them, then cheating is just going to make them feel horrible. If you care that much, you've gotta stop that before it goes any further. Do not get back into a relationship with your ex right now... three-timing is just going to make things worse. You need to break off with one of them gently, and then work out which of the other two you want to be with.
And from now onwards, think VERY carefully before you get into another relationship, whether you're going to just end up hurting him.