Dumping My Educated Youth Fiancé, the Drama Queen Supporting Character Shocks the Whole Village

[Historical-era novel transmigration + happy ending + one-on-one romance, quite sweet] She thought that after transmigrating into the body of a cannon-fodder woman in 1977, all she had to do was take revenge on the "former educated youth's sweetheart" and her "green tea rival." So how did she end up being cherished and doted on, inexplicably holding hands with a rich, handsome man from the capital, making helpful mentors and friends, and somehow working hard until she reached the peak of her life?

That rich, handsome man, who seems so much like someone from her past, is hiding a secret!