This is a difficult one but if you both want to get past it lets see how it can be done. I am not judging you so try and read through what I wrote, I am far from perfect but I think if you pause and really look at yourself and are able to feel the shame and revulsion you should be feeling that you will be a better person for it. Some people have no capacity to feel what others feels and with out that, they are beyond anyone's help and should be kept apart from the rest of humanity. Murders and child molesters fall into that category.
Sit down in a quiet place and write out how what you did effected her so grievously. What I mean is, it not enough to say you are sorry but that you must put yourself in her shoes and see your actions the way she sees them. That will take some compassion and empathy on your part and some pain if you are really sincere. You will have to go where she has been in her childhood and experience the evil that has been visited upon her. You will have to experience how you actions were reminiscent of that evil and how your actions have stirred up memories of being invaded and depersonalized. If you cannot feel the enormity of her pain at being sent back to that dark place by a person she trusted then I sincerely hope she stays strong and does not let you back in her life.
As you say it, you have done this before and got away with it, which is a testament to the capacity of women to deal with and tolerate men and their sexuality which is sometimes ugly. You should have been charged with sexual assault because that's what you did. You did not have the consent of the women you touched and yet you did it anyway. You did you did not consider not consider the woman you assaulted before and you are not considering this woman. Now is the time to do that, now is the time to become a helpless little girl and feel what it is like to be violated or a woman and feel what its like to have a man you trust use your body without your permission.
Give it time and feel it all. Now do you understand why people her have reacted the way they have to your request for help? I am not judging you, but I am asking you to judge yourself. You have no idea what you have done because you have not experienced the pain she has. When you say you have done it before to other girls, you realize that you assaulted women and you think that they should have great fun with it, you simulated a child-molester in your assault of your girlfriend and thought it was great fun. Can you blame the people here that they find you repulsive and what to get rid of you? You have no empathy towards women and that is dangerous and inhuman.
She is a survivor and she needs people in her life to be her protectors like the parents that were missing to protect that little girl. She will never get the unconditional love of parents but if she could get the love of a man who has the strength to go where she has been and to be as much of what she needs him to be as possible. She can enjoy her life now but she cannot have anything done to her that smacks of what she experienced in her childhood.
You did something that was criminal and morally wrong, Moreover you did it to a woman who has experienced unwanted sexual contact as a child - you were simulating a child molester for her. I am not saying these things to judge you but to try to get you to see how serous a violation you actions are.
Her leaving was a sign of strength, it is very difficult for abusers of child abuse to act on their own behalf but she did. If she asked the question I would advise her not to let you back in her life and I would support her very healthy move away from you. I would tell her to find a good strong man who will understand her strengths and weaknesses and who will stand with her like a man and protect her like a man and leave the criminal behind
You can't fix this because you most likely are not the right kind of man. If it has never occurred to you that touching a woman no matter what the nature of you relationship without her consent was wrong then you are not really good for anything,
If you have any redeemable qualities, simply try for understanding. When you understand really understand you should feel shame and disgust with yourself then you know you got it. After you experience that, then forgive yourself and vow to consider carefully all your words and deeds and mare sure you are not wronging anyone.
After you do those things come back and read these post again and if you still feel they have been unduly harsh don't bother to post again because you still don't get it.
This is harsh but you need a hard appraisal, if it makes you angry and defensive so be it. But all the reactions you got here is a fair and honest reflection of your effect on people. You don't get often so use it wisely. I hope you will take this in the spirit in which is is given, an attempt by one mortal with a fractionally clearer view of the situation to aide another with a very clouded view. I an equally hopeful that this woman can move on with her life without further contact with you.