Tell me what happened. I've been there for her. I was there when she needed a shoulder to cry on, a hug, a kiss, and mostly of all a hand!!!
She cheated on me about 7 times, but I was so determined to help her. That was my goal and dream for me and her. Slowly I was doing a good job, and she was doing what I was telling her, but at the end it just seemed that I wasn't enough for her or my heart or even my love.
So I told myself that there was nothing left for me to do but to let her go. I told her if she wanted to live the life where she hurts herself, and the people around her, or live the life that she knows that someone is there for her and loves her? But who knows?
Please tell me, what did I do wrong?
Your question what did I do wrong is the clue to your problem.
I know that you were raised by a parent (or parents) who abused you and didn't love you properly. All abused kids try to take care of or fix the damaged parent. Because all children feel omnipotent (meaning, all powerful), they actually believe that they do have the power to fix their parents.
So when the parents doesn't change, the child feels that he/she failed. But of course, the child can't give up. He's omnipotent after all! So he just tries harder to fix the parent. It's no surprise that this pattern will continue into adult relationships.
If you read what you said to me, you will see that you tried and tried to heal your girlfriend. It didn't work and you feel you failed.
First of all, we need to let go of the omnipotent fantasy. You didn't damage your parents. You couldn't heal them. The same is true for your girlfriend. Once you stop trying to fix the other person, you can then get down to the real business at hand. You only want to fix the other so that you can once and for all be loved and healed yourself.
So let's cut to the chase and love and heal you. You know what you always needed as a child and didn't receive. Now, instead of being the perfect caretaker to people who are broken beyond repair, be the perfect caretaker to the little abandoned and abused boy inside yourself.
Talk to him, re-parent him, love him. When the little guy inside you is healed, he will be ready to find a new life partner, one who is capable of loving him as much as he loves himself!