The ruling on one who swears to abandon sins but then commits them

The listening brother (A. B. K) from Duhok Governorate, Iraq, says in his message: I am a Muslim young man, twenty years old, unmarried. I have fasted the blessed month of Ramadan for nine years, and I pray according to the proper manner, praise be to Allah. I love my religion, Islam, to a very great degree, and I have completed the recitation of the Qur'an many times. But, unfortunately, I have a high sexual desire, and I committed a great mistake and then repented. I swore that I would not do it again, and if I did, I would not be on the religion of Islam. I committed the same mistake again, and unfortunately, I have now repented to Allah and will not do it again, if Allah wills. Please guide me on how to purify myself from the punishment of Allah? And what should I do regarding this oath? May Allah reward you with the best reward.
Answer: Praise be to Allah who guided you to repentance and showed you the way to it. Be glad, my brother, that you are on the right path, if Allah wills. Repentance wipes out what came before it. Even if you were to return to it, as long as you repented with a sincere repentance both at the beginning and at the end, praise Allah for that. Allah the Mighty and Majestic said: [An-Nur: 31]. He made repentance the path to success, so you have succeeded in that, if Allah wills. The Prophet (peace and blessings be upon him) said: meaning: it removes what was before it and demolishes what was before it. If disbelief, which is the greatest of sins, is repented from by a person, Allah forgives it, as He said: : [Al-Anfal: 38]. Disbelief is the greatest of sins, and whenever a person repents from it, Allah accepts his repentance, if he repents sincerely, regrets the past, resolves not to return to it, and abandons it. So Allah turns to him in mercy. Likewise, for zina and other sins, if a person repents from them with a sincere repentance, regretting the past, abandoning the sin, and making a sincere resolve not to return to it, then Allah erases it from him and forgives it for him. As for the oath, you must pay the expiation for the oath. Your oath requires you to pay the expiation for an oath, which is feeding ten poor people, giving each poor person half a sa' of dates, rice, or other staple food of the country, or clothing them, giving each one a shirt or a lower garment and a cloak. This is the expiation for your oath, praise be to Allah. We ask Allah for you steadfastness upon the truth and safety from the stings of Satan, for He the Mighty and Majestic is generous and bountiful.