So I'm a bit confused about what happened after Jade realized she was asleep before [S] ==> MSPA Reader: Have Mental Breakdown (or something like that), so what's happening right now is the timeline where John died, as well as Bird Dave, and Jade didn't go Grimbark, Terezi and Vriska are both alive and well, and John didn't put his arm in the Juju, so the Terezi Scarf Adventure happened in a different time line, and that's why John and Roxy are now with the rest of the gang? (sorry if too much)

Jade still went Grimbark she’s just asleep right now because Vriska put her to sleep. Pre retcon John and Roxy escaped from the Game Over timeline and zapped over to this new timeline after John retconned out Vriska’s death.