I liked your long not-sent letter. Mine's up to about 55 pages by now, but I suffer from Prolixity.
I liked best the part right in the middle. Where you tell him, essentially, to put up or shut up.
There's really only two questions that are relevant, it seems to me:
1. Why should I be friends with you?
2. What does "friends" do for you that "spouses" doesn't?
Until and unless he can answer those questions, I'd tell him to take his mesh Euro-weenie underpants and his Friggity Frog Smell-Sweet Sh*t and his cravat and take a bloody hike.