Genius Mom, Supreme Baby

In the Shenwu Empire, Ye Chuyue is known as the stupid, ugly one, the woman who went with somebody and had a child by him. Her fiancé marries another woman, and on the wedding day Ye Chuyue puts on bridal clothes, climbs the city wall and jumps. The body wakes up with someone else inside it, the head of an old martial school from the twenty-first century. She goes after the people who built that reputation and starts clearing her name. The empire had written her off as useless and slow, and she turns out able to shake the place by hand and to settle fighting a thousand miles from where she is standing. The boy everyone calls a bastard is the Emperor's son and carries the bloodline of the Heavenly King.