As difficult as it is, you have to let go and then help yourself. It was really difficult for me to tell my H to just go do what makes him happy and I would do the same. And it was hard to start thinking about a life without him. But, since I have started to plan for that possibility, I am much calmer and I don't feel like the weight of the world is on my shoulders.
Sure, I still think about it a lot and I pray that he will come back to me, but, like Job said, we didn't break them and we can't fix them. All we can do is take care of ourselves and, in your case, your son.
Hang in there ... Take care of yourself and take care of your son. I will say a prayer for you.
Me: 59 and holding H: :53 Me: 1 S, 1 D, both grown M: 19 T: 23 BD: 9-23-2013