I think that leaving you hanging, neither divorced nor married, is cowardly on your husband's part. If he doesn't want to be in the marriage, he should just say so. What he is doing is cruel. You can't move forward either to save your marriage or move on past the break up.
I agree with Mahonri. Your son probably knows more then he is saying. I would guess that in an effort to not take sides, your son is keeping certain things to himself. Maybe not an affair, but there is no way your son could live in the apartment with your hubby and not discuss this with him.
I'm sure it will be tough, but you're right, you WILL get through this. I agree with the others who say your son may be trying to stay out of the middle. I guess your husband will, eventually, get around to telling you his reasons . . .
I'm so sorry honey. Keep trying to figure out what is going on. There is no way I would give up 32 years of my life without a fight and without knowing exactly what is happening.