I Took My Cousin's Place as the Bride, and Now That I'm Thriving, She's Miserable

(Period setting + pocket dimension + raising kids + stepmother + everyday family life + marriage before love) Qin Wanwan accidentally transmigrates to the 1970s and becomes an early-death cannon-fodder supporting female character in a period novel. From the start, her scummy father forces her to take her cousin's place and marry a veteran whose legs are disabled. He has also adopted the two children of fallen comrades. Everyone says she'll be stuck in a loveless marriage and live a miserable life. Her aunt and cousin are both waiting to laugh at her. Who could have guessed that her disabled husband would make a full recovery before long? He's incredibly vigorous, and on their first night after his recovery, she conceives multiples. From then on, their days together are sweet and blissful. But wait! It turns out her husband is hiding a huge secret! Qin Wanwan is busy enjoying the gossip when she accidentally exposes the affair between her scummy father and aunt, sending the pair of lovebirds to prison. In the book, her cousin is the heroine. In her previous life, three powerful men pursued and doted on her, and she used them to become the richest woman in the country. But in this life, the powerful men have all seen through her true colors and told her to go cool her heels somewhere else...