Read Counterattack Through Pregnancy/ Deliverance Of The Counterattack manga
Having a two-faced bitch as a love rival isn’t scary… What’s scary is that the bitch has the upper hand—reincarnating as his little brother! Due to his “little brother,” his lover was snatched away, his grandfather suffered a terrible death, the family business was taken over, and on top of all that, he was chained and thrown into prison.
However, on the night before his release, he got laid by a man in the midst of confusion and became pregnant. After he got out of prison, he came back anew; he opened a restaurant and made a fortune while raising his child. He lived a vibrant life but certainly didn’t forget to deal with his horrible ex and bitch.