Although Jade had managed to handle herself really well earlier, she was quite shaken by the time she parked the car in front of Tom's mansion after Harry had left.
She didn't step out of the car immediately but remained inside with her head resting against the wheel as she thought about her carelessness and what could have happened had Harry not saved the day.
She didn't necessarily regret riling Rebekah up to the extent that she had acted the way she did. What she regretted was not being careful enough and not actually sharing her plans with Harry beforehand.
She had underestimated Rebekah's wickedness, and that could have cost her life had Harry not been a step ahead.
What if his men had not been watching her from a distance? Sure, if anything had happened to her, they would easily have known Rebekah was behind it, but that would have been long after the deed had been done.
