The Billionaire's Regret Chasing His Runaway Bride and Heir by Cyra McKenzie

"I need a fake fiancée for three months. You live here. You attend events with me. You pretend to be madly in love with me, and you annoy my grandfather by simply existing. In return, you get this check today, and another one for the same amount when the contract ends."
He took a step closer. I could smell the champagne on him, sweet and sharp.
"So, Andrea Rostova," he said, holding the check out to me. "Do you want to go back to washing dishes and drowning in debt? Or do you want to play a game with me?"
Desperate to save her sick mother, Andrea agrees to become billionaire Maxwell Harrington's fake fiancée. What begins as a simple contract soon turns into something far more dangerous as fake kisses become real feelings.
But Maxwell's jealous ex manipulates him into believing Andrea betrayed him for money, and he cruelly throws her away.
Pregnant and heartbroken, Andrea disappears.
Four years later, Maxwell discovers the daughter he never knew existed. Determined to reclaim his family, he forces Andrea back into his mansion with one ruthless ultimatum: return to him for six months, or lose custody forever.
Now Andrea must decide if the man who destroyed her heart can truly become the man willing to protect her at all costs.