Stepbrother At Last by Stephanie Brother

Do you ever look back at one day in your past and know that if you changed just one thing on that one day, your whole life would be different now?

Three years ago, stepsiblings Julia and Nick found everything they ever wanted—each other. But their dreams of a future together were ripped apart in one violent moment. Nick walked away from the accident without a scratch. Julia didn’t walk for two years.
Separated since that day, Nick and Julia have taken different paths. While Julia struggled to put her life back together, Nick became a brand-new tech billionaire. Each is sure the other has moved on. Now Nick is back in town and he needs to know just one thing:
How much does Julia remember from the day of the accident? He’ll give anything, down to his last dollar, to win her back. But after what he did, how can Julia ever trust Nick again?

This is a standalone novella with no cliffhangers.