Aren't you able to sleep? I was noticing the time of your posts and am hoping there is some other reason you are up at such an ungodly hour.
My H left when the kids were 13, 16, and 19. The oldest was already away in college. I worry most about the middle son. You see, the youngest one will go stay with xh some weekends (not many, but some), but the middle one refuses. He (middle son) works mainly in the evenings, so he misses all of the pop-ins that happen here despite my many requests for the xh to respect my house. So, he sees so little of his dad. I think it would be ok if xh hadn't been such a wonderful father up until that point. He was the best father I knew, so it is hard to come to terms with the shell we are left with. Xh doesn't seem to get that it is up to him to keep the relationship with his son going. He is the (ahem) mature one in this situation.
My kids expressed the same feelings as your son- they they didn't want to see their dad. My oldest son went to his dad's apartment for the first time just a couple of months ago. Middle son still refuses. But, like I said, the youngest one came around. It is now that he is getting older and wanting to do other things that he is not that interested in going.
Maybe that letter from your son will help him to open up dialogue with your H so your son can express his fears for the future.
I still sometimes feel like I am drowning, too. But, those times get fewer and farther between.
I got a text from my xh at 1 a.m.... telling me he missed me. I would have killed for stuff like that once. Now it just puzzles and annoys me. Before I would have analyzed it to death- "why is he thinking of me at 1 a.m?"..."Does he think of me a lot?"...etc. Now I know that those are just empty words on a screen. It is the actions that I need and will probably not get. So, I rolled my eyes, rolled over, and went right back to sleep.
Yes, T, you do need to be strong for your kids. But, don't forget to take care of you. What are you doing for YOU these days?