I'm pretty sure Secret Society had a little note to say it takes place after the events of Forever Evil #1.
Justice League #30 is the beginning of a new story. While it deals with fallout of Forever Evil, it won't really have much to do with Forever Evil itself.
Well its been a while since I read it but wasn't SS the issues with Owlman, the joker, Outsider on Earth 3? Of course there could have been other scenes I'm forgetting lol
Most of the issue is like an extended flashback. So a lot of it is the origin of Outsider and Owlman on Earth-3, but the present day stuff occurs after Forever Evil #1.