Can you really get your ex back? And how?

For the past year I have been fighting for my ex to get her back. We have had a great three year long distance relationship. When she was out with her friends she sometimes got hurt and caused me to worry, and I called her when she was out with her friends just to make sure that she was okay. Becuase of that I was labeled controlling/posessive by her mother and her friends. It was during that time when we split up, as it was her mothers idea to see other people and get together later on. It was one of her best friends who convinced her to dump me and go out with him. I have given her one month and two weeks of ''space' by her request. Her mood changes to her own friendly peronsality to down right nasty. After six months, the guy dumps her. I have treated her with respect, honesty and love, and yet she treats me like I have done something worse. She has told me things like 'be strong, And it'll work out between us in the end.'' Now she says it wont work out.What can I do to get her backCan you really get your ex back? And how?
i ruin my relationship with my girl recently.....after 3 years and a half...i wish i know the answer too