Will this work...its my last resort?

Uhm well it depends on whether he REALLY likes her or not. If he doesn't like her as much, then he probably will dump her. But do you really want your friend's happiness to suffer because you dislike her boyfriend? Although I'm sure you really do hate him, think about your friend for a sec. Is he rude and an to her? Or is he sweet and kind? Does he seem to regret being disloyal? Does he deserve her? Do they each want to be with the other? If you're willing to put aside your friend's feelings for your own personal gain then go for it. Break them up. Ruin your supposed friend's relashionship. Who am I to judge you?