abuse and moving on

I have been on and off with my abusive/cheating finance for two years. a big part of the verbal abuse and cheating is due to his alcohol and pharma addictions. when he is sober this man is the man of my dreams, but despite my begging and pleading, he always chooses his vices over me. I need to get over this once and for all. Ive tried so many times and so many things to get over him, but he never leaves my head, im just always stuck on the things he has said or did, and I always want him back no matter what he has done. any personal stories or advice would be so helpful.