You are doing the right things right now. You are reaching out for support from recovering people, you are reading about codependency, you are self-reflecting, you are making a choice to get healthier. All of that will put you on a safer path but it will not erase the grief. The heartache you feel is tremendous grief and shock. It is also the effect of being emotionally abused.
Men in active addiction abuse the women who love them. Your addict abuses you with every text, every phone call, because he is using you. He is using you as an object, a distraction, and an ego-booster. His phone calls and texts are SELFISH. He is completely self-absorbed and self-seeking in his addiction and he does not really care if you are all right, or if you are in pain, or if you are safe in this world.
After the period of grieving, I hope you will be restored enough to yourself to see his manipulations as the worst form of addict behavior: exploitation of a vulnerable human being.
I don't know what his DOC is, but if it is crack or heroin or oxy or whatever: the next time he contacts you, tell yourself "Crack is knocking at my door again." Insert the appropriate DOC. Ask yourself why the drug is seeking YOU. Is it because you made it more comfortable? Is it because you made your abf think he was a normal guy if he was in a relationship with a nice woman? Is it because you were helpful when he was out of control or coming off a high? Why is his DOC calling you?
When we realize it's the drug calling, it's easier, I think, not to hurt so much. And to toughen up. We have always idealized the addict in our minds, we romanticized him and created in our minds a picture of him as hurting, vulnerable, sensitive, lost. We think we have lost someone amazing, someone we connected with heart and soul. That is how seductive drug addicts are. They actually create the illusion of being deep and soulful and loving human beings.
But they are just using people. Scanning the environment for props to keep their habit going or for someone who will be yet another source of escapist pleasure.
Do not let him decide for you whether you are worthy of being treated as a valuable and precious human being. He is just playing you. The way he plays everybody who crosses his path.
When you get that, your pain is going to ease.