السلام عليكم ورحمةالله وبركاته
I am a married man with 5 children .
12-13 yrs ago some events took place in my house which led me to believe that my wife was cheating on me .
I didn’t take any drastic action to hold my family together took her for Hajj and thought I will be able to forgive her and move on.
But I have a deep resentment of these in my mind and not a week goes that some of those events play in mind making me feel very agitated , disturb my prayer , behaviour and especially dealing with my wife. Despite my efforts I don’t seem to be able to control all this . I always feel guilty for not being able to give best treatment to my wife due to all this.
What’s the best way to deal with this please that will allow me healthy state of mind .

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

In general, protective jealousy over one’s womenfolk is required in Islam and is a laudable attribute for a man provided that such protective jealousy is founded on valid doubts (supported with circumstantial evidence) and not mere suspicions and delusions. If such doubts are groundless, then you should believe that your wife has not committed any sin instead of thinking badly of her. Allah, The Exalted, forbade that in His Book as He Says (what means): {O you who have believed, avoid much [negative] assumption. Indeed, some assumption is sin…} [Quran 49:12] It was narrated on the authority of Abu Hurayrah that the Prophet, sallallaahu ‘alayhi wa sallam, said: “Beware of suspicion, for suspicion amounts to the worst form of lying…” [Al-Bukhari and Muslim] In this case, it is incumbent on you to ward off these suspicions; seek refuge with Allah, The Exalted, from the accursed Satan; and recite Thikr (remembrance of Allah) abundantly to calm your soul and reassure your heart. Allah, The Exalted, Says (what means): {Those who have believed and whose hearts are assured by the remembrance of Allah. Unquestionably, by the remembrance of Allah hearts are assured.”} [Quran 13:28]

As for what you should do about your wife, the criterion should be her current state; if she is upright and has a good reputation, you should keep her as wife, live with her in kindness, and strive to forget what happened in the past. Do not let Satan find his way to you, for he always strives to separate a man from his wife.

For more benefit on husband's praiseworthy or blameworthy protective jealousy over his wife, please refer to Fataawa 237010, 90757, and 156495. However, if you are still suspicious of her conduct but found a way to rectify her in order to protect your family, you should do so, or else no good lies in retaining your marriage with her, and do not torture yourself because of her. In this case, it is recommended for you to divorce her, as the scholars mentioned.

It is noteworthy that husbands should keenly instruct their wives to adhere to the teachings of Islam, foster their faith, and edify them on their religion. Allah, The Exalted, Says (what means): {O you who have believed, protect yourselves and your families from a Fire whose fuel is people and stones…} [Quran 66:6] When faith is deeply rooted within the heart, it prompts a woman to adhere to righteousness and guard her husband in his absence, as Allah, The Exalted, Says (what means): {So righteous women are devoutly obedient, guarding in the husband's absence what Allah would have them guard.} [Quran 4:34] As-Suddy said: “It means to guard her husband in his absence with regard to his honor and wealth.”

Allah Knows best.