No, letting her go like that would only drag it all way to long and make it a long slow knife.
Just be honest.Meet her,(do it in person, say you need to talk to her) tell her whats on your mind,and that you find it better that you two should break up. Tell her your feelings, just as you exposed them here.
Believe me,its hard to do it the honest way, but it will hurt her a lot less.
If you did it as you plan to do it, it will make her wonder whats going on, why youre acting like that, and it will be weeks (or months) of agony for her.
Just one clean cut and its over.
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\"Isnt it a pity?Now isnt it a shame, how we break each other\'s hearts, and cause each other pain?\"