>>38427723She wanted to save the world and die heroically because she couldn't cope with the death of Aster. She was willing to do the sacrifice because she got nothing left to live for and didn't want Devon to potentially hurt other people and ruin another's world fate. Her words before attempting to blow herlsef up in space were actually we are gonna see each other very soon or something like that so she was really willing.
>>38428792Alternate dimensions have been known to exists in the pokemon world for a while, there are books published about it you can read in Canalave library because Sinnoh natives believed Palkia created them. ORAS itself exists in an alternate timeline.