I have an ex wife I had these feeling for. She and the nigger she screwed have both been in the scope of my rifle many times. Yet I did not pull the trigger. I am glad I did not, if I had I would not be free today.
So I did the opposite, I forgot her completely. I remarried a great wife who I can trust. She and I have 22 years and two wonderful children. She and I have a GREAT home and life. While we have all the good, she has had the bed. from the problems in her own family, to the loss of her job and home.. She had to meet me and have me sign papers a while back. I showed her pictures of my children and told how happy I am. it ate her up, and her friend told me how much.
Just get on with your life and let her go. May take years, but you will get by this.