What is the ruling on one who repeats inwardly the suspension of divorce upon a condition, and what is the ruling on one who utters divorce by mistake?

All the whispers mentioned do not entail divorce. Therefore, you must completely disregard them and beware of indulging in them, as their consequences are dire. Seek Allah's help and occupy your time with what benefits you in your religion and worldly life. You can also refer to previous fatwas and the psychological counseling section on the website for further information.