I understand the pain and the hurt... it also does not make sense that you are succesful and hooked to someone like this - a real partner would also be responsible and own a home, etc.
I realized I go out with unavailable people because it feels familiar and because my LOW self esteem - how I see myself is such a distorted picture that in order to feel good about myself I have to be with someone else that is "lower" at some level: not working, or lost in addiction, etc.
I hope you can go to therapy, its eye opening! in my case it took long months to go to one........ I hope you don't wait so much.
You are a special lady and slowly your mourning will become wisdom. Melody Beatty calls it "the healing process". This is feeling is not going to last forever.