I am close to this situation. My fathers wife lost her teenage daughter in a horrible car accident 4 years ago and she is still grieving. She functions, but she will never be the same. She is an inspiration to me, she is full of grace, but she is as fragile as a crystal glass. She still goes to therapy every week at least once a week.
I do not think I would ever get over the death of my child. Yes, you both have a 2 year old, but he had the other child for how many years? It was tragic accident, so not a long illness to prepare for a death? How would you truly feel if your 2 year old died?. How long do you think you would need to get over it? 3 months? 6 months, 12 months? Ever?
I think you need to also go to counseling on your own you sound very angry (which is a natural way of grieving a tragic car accident) and then the 2 of you need to go together. I am thinking your husband is extremely depressed and needs to continue to see the counselor he feels the closest to. Depression makes a person exhausted, unmotivated and distracted. Things run through your mind so quickly and so consistently, he may just need the break in his mind.
The xbox is a distraction. Maybe you could make a deal with him to only play on the xbox when your 2 year old is in bed. Please be there to listen, not to be upset about his behavior, what you think he should be doing. You are his wife not his mother.
I am sending you strength and patience. You can be his biggest supporter, he needs you now more than ever.