What is the status of the project's capital and profits, is it permissible to benefit from them, and what should the questioner do to purify his money and calm his soul after his repentance, knowing that he committed thefts, returned part of the money to its owners, and donated another part as charity?

Your work in a mixed hotel, whose activities range between lawful and unlawful, necessitates purifying the money you earned from it. As for the money you have spent, repentance is sufficient for you. Regarding the remaining money (salary and commission), you must give out the portion corresponding to the unlawful activities. If determining the exact proportion is difficult, then donate half of it as charity. The amount you took from the hotel (12,000 pounds) must be returned to its owner. You have done more than what is required of you by Islamic law by donating large sums, and this purifies your money and makes it lawful.