If memory serves me, doesn't he have physical/medical reasons that affect his desire? Did he ever get his testosterone level checked?
I guess the big question is whether the rest of what the two of you have together is enough to keep you in the marriage, even without sex. That question is too important to be fully explored here--I hope you are talking to your psychologist about this issue. You'll have to weigh the importance of your son having both parents, your ability to raise him by yourself while having to work, and all the other issues that come with such a decision. I can imagine it must be hard to keep your self-esteem at a healthy level when your husband doesn't want to connect physically.
(If by any chance your husband is on an antidepressant, that can really affect desire as well as make getting an erection much more difficult).