If I am calmly I live you alone, trust me I'm not coming back

You cannot force it upon anyone, which I'm guessing you already know. And by fighting for some one who has already left is forcing. It does not make you a hero or a fighter with a cause, but more like a deranged individual. If you truly love the person, then set her free. In a fairy tale setting they say if she comes back, means she truly loves you. Frankly speaking I wouldn't wait around for her to come back, but in the wildest possible chance she does, I would choose to give the middle finger and move on.