STH, I didn't think W2's and tax returns are necessary for a school enrollment but maybe to establish residency in a particular district? Why does she lives so far away from you know by the way? That sounds really inconvenient a lot of time for your son to be sitting in the car going back-and-forth.
I have the same problem as you not knowing how to respond and thinking all those thoughts and not being able to respond in a happy and carefree way. Sometimes we just have to do our best but this is the hardest thing ever. It's so hard to avoid shouting "maybe if you just came home and we could be a normal family again we wouldn't have to have all these conversations!"
I hope your son gets through all this ok. I'm so sorry for you and your son. I hope this situation gets better whether your wife comes back or not.
