Started making the dreaded "I have sad news" calls to friends. Since I don't confide much in other people about what is going on and maintain a facade to the rest of the world, it's a little disenchanting that so far only one person has been surprised.
The hardest part is feeling like I need to explain to the people who haven't been around us very much. One of my friends just assumed we'd grown apart during our separation. I thought, "How facile! Like I'd give up on my marriage over anything short of dire circumstances." Alas, I'd rather go with that version in public than the truth that our R is just one huge tangled mess of distrust, anger and resentment.