Assalamu alaikum wa rahmatullahi wa barakatuh,
Lately, I have been having waswas about taking revenge against a bully who beat me up in high school 6 years ago. At that time, I was very vulnerable and weak, but now I'm not that person anymore. So should I do it, or forget and forgive? This is really driving me insane.

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

Firstly, we would like to thank you for your trust in us, and for turning to us for advice and Fatwa; we implore Allah, The Exalted, to reward you generously.

If this person assaulted you, you have the right to retaliate proportionally against such an offense; rights are imprescriptible as underlined by Muslim scholars.

It is allowable for the wronged person to retaliate proportionally against assaults, provided that he does not exceed the extent he was wronged. However, pardon is better and yields greater benefits in the worldly life and the Hereafter. For instance, it is one of the means to earn the love and forgiveness of Allah, The Exalted; He Says (what means): {… and let them pardon and overlook. Would you not like that Allah should forgive you? And Allah is Forgiving and Merciful.} [Quran 24:22]

It is also a means to join the righteous and doers of good; Allah, The Exalted, Says (what means): {Who spend [in the cause of Allah] during ease and hardship and who restrain anger and who pardon the people - and Allah loves the doers of good.} [Quran 3:134]

Moreover, it is a way to have one’s honor increased; Abu Hurayrah narrated that the Prophet, said: "Allah increases the honor of the one who forgives and pardons." [Muslim]

You should also bear in mind that his assault against you dates back to high school, and young people at that age tend to be rather reckless, and indiscretions are conceivable on their part during this phase. Therefore, it is advisable that one should disregard such matters as he gets older and wiser.

You should strive to let go of such thoughts so as not to allow the devil to overwhelm you with distress, anguish, and grief. Helpful means in this regard is keeping in mind the above-cited texts about the merits of pardoning others’ offences and reflecting on the great rewards it yields in the worldly life and the Hereafter.

Allah Knows best.