Cannon Fodder? I'm the Queen!

Her husband sends money and never comes home. He is a CEO. She is married to him because that is how the novel goes: she died and woke up inside a book she had already read, in the part of a minor character whose life is supposed to end badly for the heroine's benefit. Her husband is fixated on that heroine. Her adoptive sister is two-faced and schemes against her, the family that raised her is not hers by blood, and they have been using her as a tool to steal her father's luck. She refuses to play the part as written and takes on the sister and the family head on. During a live broadcast she gets up and sings, the performance gets attention, and it becomes the start of a career. Her husband begins to take an interest in her for the way she stands up to them, lets go of the heroine, and helps her expose what the family has been doing.