Married Off in the '80s: Remarried to the Roughest Man and Carrying His Twins

[Alternate History + Double Virgin 1v1 + Domestic Life + Rise to Riches + Rebirth & Bride Swap + Military Marriage + Male Lead’s Secret Crush + Marriage Before Love]
Song Qingdai died.
She died after years of hard work raising her husband’s three children from his previous marriage.
In her past life, she was forced by her adoptive mother to marry a divorced man with three kids. Everyone waited to see her fail — but after the marriage, that “old man” built a successful company, and the three stepchildren all went on to have thriving careers.
For a time, she was admired by everyone.

Meanwhile, her younger sister, Song Mingshan, married the man Song Qingdai was supposed to — under their parents’ arrangement — only to suffer brutal domestic violence, fall into mental instability, and ultimately, during a live interview, stab Song Qingdai to death.
When Song Qingdai opened her eyes again, both she and her sister had been reborn…