God, poor you. And your poor kid. I was teased about my weight and it still hurts to think about.
So. I'm new here too, but I wanted to reply and say welcome and somebody with more knowledge will be around shortly.
My son does a lot of the same things (overreacts, rages, etc) so I'm sympathetic on that score. The stuff about your husband jumps out at me. Maybe your husband could use some counseling to deal with his feelings towards your son. Why were you the sole working parent for ten years?
I have to say--I know this probably isn't all of it, but--I wouldn't discount the medical stuff too quickly. Yes, the surgeries aren't anything new, but as he gets older he gets more awareness of what's going on and more fear. Does the hospital have child life specialists to talk with him about these feelings?
Have you consulted with your county's mental health office?
