I'm sorry you are in such pain. You aren't stupid...you are doing the best you can. Recovery takes time and is filled with baby steps. You left when things were bad...it doesn't have to be forever. Good for you, doing what you need to keep you and the kids in a good place.
I am not in your situation, but what I read here all the time is that when it is truly time to part, you will know.
I don't believe our addicts do not care; I believe they are incapable of caring when in active addiction. The drugs will always be first and the disease will do whatever it can to protect itself. It always helped me to separate the addiction from the person I loved...Helped me to find compassion and to not feel it was all my fault. Hugs.