Someone once asked, 'If you could take it all back, would you?' At the time I didn't know. Now I do. I wouldn't take that terrible experience back for anything in the world. Too much light has come out of my darkness.
If God is the source of all things good (love, light, connection, grace etc etc), being separated from him is to be separated from all things good. So imagine an eternity of being alone in darkness, disconnected.