Does that work for you too?
My opinion is honesty though.. there is no such thing as the "perfect break up line".
I had a rather good breakup experience though, went to tell her it was over. Started with the "it's not you, it's me.. I just don't feel like being in a relationship".. long story short, I f*cked her for a while and gave her the last taste of my man juice and left by saying "This doesn't mean it's not over though.. because it is".
But she hates me though, so if you don't want her to hate you I don't recommend this method.