I don’t know if you have tried this…..
Just sit down and write her a letter.
“Dear Mimsy,
It was very difficult for me to end the relationship, but I felt that it would, in the end be the best for both of us. I know that it hurt you deeply and that you are probably angry with me. I don’t blame you. I feel that what we shared was very, very special and my life will be forever changed because you were in it. This probably isn’t much consolation for you. I just wanted you to know that you meant a lot to me, and even though the idea of remaining friends with me seems the last thing you would want to do, I hope that one day you might find it in your heart to forgive me. I would like nothing more than to have a friendship with you when you (if ever) feel ready to do that. If not, I wish you every possible good thing for your life. If so, you know where to find me. You are a very special person and someone out there is going to really be blessed to have you in their life. Thank you so much for sharing your life with me. Always, Joker”