I'm glad you took the time to give the confession. I feel for you. I'm not offering advice, just a similar story. I've posted it all over the internet for her to see, hoping she'll see it one day and contact me, that day never comes.
I was doing drugs and treated her like hell. I cheated on her all the time and we were not together that long. When she started dating someone else I stalked her and made her fear me. She was young and scared. There was nothing I could do to win her back. I got my life back together.....then I seduced her. She was such a giving soul and believed in forgiveness--she gave in. It was her fiance she was cheating on me with. He treated her like hell too and cheated on her as well. She never deserved it.
She left him and I thought there was a chance and she turned around and used me right back to "get over him". I was a rebound but I thought she was mine again.
I gave her a ring she refused and I've never seen her since. That light that was once there was gone from her eyes. I KNOW she will never trust me again--if any man for that matter...but I would just love to hold her hand again and have her in my life in some way. Once that trust is gone, it's a downward spiral. Women like her will never forget.
Good luck