I wouldn’t I think of most of my exes that I’m friends with on FB as FRIENDS. If they are just exes, they are not my friends and I don’t associate with them on FB.
I don’t elaborate on my friendship status with people who are not related to me. I don’t say “Former BFF from middle school” and I think ex boyfriend is just TMI for facebook friends.
Friends are friends no matter what the status. I do put them in categories so I can send messages to groups. (Like nobody but my summer camp friends would care that they moved our summer camp from the old place to a new camp across the State..)