First of all, take a deep breath. There is no doubt that you are experiencing something very stressful and have every right to feel hurt, sad, and angry. While I have never been married, I am currently recovering from a failed relationship and am also trying to adjust into this semester of graduate school.
It doesn't seem like your counselor is helping you get through this. I tried two counselors before I found one who clicked for me. She made a world of difference on my perspective and slowly but surely, helped me through the stress.
While you changed your life to give your husband a second chance, and it didn't work out, rest assured that you have been successfully raising your son on your own for 6 1/2 years and you will be able to do that again. It is obvious that your husband is suffering from something mentally or just is not capable of fulfilling the husband/father role you were hoping that he would.
You are strong. You are going to feel bad for a while. You will pull through this. You will get through school and you and your son will have a wonderful life.
Baby steps, though. Just know while things are messy now, they will be whole again. Keep posting so we can keep helping.