I tell everyone who will listen that I don't maintain friendships with my exes. But that's putting it mildly; I don't talk to my exes. At all. Not a "Hi, how've you been". Not a dinner to catch up. Not a "pass me the salt". Nothing. In fact I once became frantic at what I would do if I ever met my main ex (guy I was in a long term relationship with) in the streets of Nairobi. Since Nairobi is not that wide, we did eventually meet .. and other than being uncomfortable, it lead to conversation I just had to nip at the bud.
The truth of relationships is that seperation isn't generally a mutually arrived at decision .. You don't generally turn away from your reading (you of 'Eat, Pray, Love' and he of 'Peanuts') to look into each others eyes and therein read the confirmation that it's over. You don't then burst forth into song and dance to a quickly made up, yet rythmical beat titled "I love you no more". Each doesn't pick their favourite of the 2.5 kids and promise to write. No. Things don't work that way.
The truth is there's always the person who's left. It's in The Script: the heart don't Breakeven. The leftee might have had an inkling that things weren't good and even done all they could to hold on to the pieces. They may have been happy & whisteling away like a kid in a candy store oblivious to Chucky hanging out in the next room. All in all it hits them hard. Like an iron fist to the gut. Shifts their reality. Drains out some of life's technicolor. And it's not always easy being the one handing down the decision either. It can change you. It can break you.
So now you have these 2 people. Both hurting. Both yearning. Both purposed to survive. So they adopt the 'let's be frends' ideology. In 'being friends', they hang around each other and maintain civil conversation. To what end, I ask? What is the point? In the best case scenario, what would happen? It's uncomfortable at best. Stalking-ish at worst. One will eventually want to get back with the other. Always happens. And then what? A river of hurt is the only sensible answer.
Be smart. Just walk away and don't get turned into a pillar of salt.