Does anybody know why the pre-New 52 Superman exists if the new 52 was simply created by Barry Allen screwing with time? Is it a different earth? If so what happened to the pre-New 52 Earth?
From what I can tell
The Flash went into the past and Doctor Manhattan used that moment to further alter continuity worse than Barry would have (this was so Morrison could salvage his pet character Barry and absolve Flash from fan-backlash) so when Flashpoint ended, the altered New 52 was created.
New 52 is an altered pre-Flashpoint where everyone has lost 10 years of their lives (which...doesn't work for characters like Damian Wayne and Tim Drake, buuuuut...). Somehow pre-Flashpoint Superman, Lois, and their new baby were missing when New 52 was set, so Doc Manhattan/Mr. Oz(?) had to create a totally new Superman and Lois in their place, so the theory is that there isn't a pre-Flashpoint Batman, or Wonder Woman, or Flash, Lobo, Lex, etc waiting to show up and meet their "counterparts"...since the New 52 versions are just "de-aged" versions of them in an altered canon, but pre-Flashpoint Superman and Lois came back and co-existed in secret.
Also, the current (red-haired) Wally West is the original pre-Flashpoint Wally because he was lost in the Speed Force, so Manhattan/Oz created a new (New 52) Wally West. Now they both exist.
I...I really gathered that on my own and fan theorizing. Its...confusing.