Hi Crying,
Breaking up is hard and your contact with your ex is dragging out the break up. Every time you reply, it gives her hope that you will reunite. Her desperate talk is most likely her last hope at drawing you back. It is emotional blackmail. If you stop responding, she will move on. It sounds cruel, but it sounds like every contact with her renews hope inside her that you can get back together. I have been on both sides of difficult break ups and I think it is harder on your end because the guilt can eat you up. You don't owe some one you dated your future. You did not marry. Dating is a time to discover who and what you want. You could never make her truly happy because you are not in love with her. She deserves some one who really loves her. You are honestly doing what is best for her by severing ties. She will be fine.