In the Apocalyptic Flood, My Sister Stole My Merman Husband

Ten years into the apocalypse, humanity discovered that Earth was temporarily uninhabitable for any living thing, so they built spaceships in orbit. Space on the ships was limited, and boarding was by lottery alone. Because I married a merman and gave birth to a rare merbaby, I qualified for a place aboard without having to enter the draw. The fake heiress, who married a South China tiger beastman, wasn't even eligible for the lottery. On the day we boarded, she used the excuse of saying goodbye to me to kill my merbaby, then stabbed me in the chest. When I opened my eyes again, the fake heiress and I had returned to the day we chose our beastman husbands. This time, she chose a merman, hoping to secure her chance of survival through a merbaby. But she seemed to have forgotten. The South China tiger is the endangered species.