TL;DR: Maintain records of out-of-band means of contact. My friends on FB are "real" friends. A few years ago, one of FB's mandatory updates swapped out all

TL;DR: Maintain records of out-of-band means of contact. My friends on FB are "real" friends. A few years ago, one of FB's mandatory updates swapped out all user profile email addresses with FB-domain email addresses. I had my address entry set to show only to friends, and I considered it (perhaps uncommonly in comparison to the common user) as a backup means of communication, including in the event of losing control -- for whatever reason -- of my FB account. When the FB update swapped my non-FB address for a FB address, I took the time to manually swap it back and to suggest to my friends that they do the same, including a brief explanation of why. If you are going to use FB and the like for significant relationships, make sure you have an out-of-band backup means of contact for said. P.S. This also presupposes, in the case of email addresses in FB profiles, actually noting same in your own records BEFORE the disconnect occurs. I.e. most of my friends also restrict visibility of those addresses to "friends only".