Wow, I like it.

Don't send it yet, you really should leave it for a few days and come back to look at it. I might make a few suggestions but I I think this is a stand up letter.

I would like to see some consequences in here, but we don't have a lot of leverage to work with right now. And my other red light is when you mentioned that your kids weren't needing the child support as much as their father my MILD concern is that he may pull that... but that's your call on how he may react to hearing that.

I will add more commentary later, but this is my first reaction.
I would like to hear what PDT thinks of this sucker too.