I am very sorry this happened to you. I can feel your pain. We have all been there. It is awful, but you will survive.
I wonder wat would happen if you just stop all contact now. Just quit cold turkey. Don't write, text, call or email him. AT ALL. Don't answer his calls, texts or emails. Have him face your absolute silence. Do it for awhile, for as long as it takes him to be jolted into the reality that he has lost you. I have a feeling you will be surprised by his reaction. Maybe you will have him begging at your doorstep.
Right now, you are making it very easy for him to hate you. Why not turn things around and make him miss you? And he will miss you! After so many years together!