To what extent are the questioner's doubts regarding his being afflicted with diseases or exposed to sorcery likely to occur, knowing that this is the first time he has committed this act, and he is regretful and angry?

You have committed a grave sin, and you must repent to Allah Almighty. Repentance is achieved by abandoning the sin, regretting it, and resolving never to return to it in the future, as affirmed by the Prophet, peace and blessings be upon him: "Regret is repentance." As for the possibilities you mentioned, their occurrence is plausible, but what is most important now is sincere repentance to Allah. It must also be noted that it is impermissible to swear by the Prophet, peace and blessings be upon him, as the Messenger of Allah, peace and blessings be upon him, said: "Whoever takes an oath should swear by Allah or remain silent."