When someone wrongs us it’s natural to get angry. Often this anger and frustration leads to further resentment and negative thoughts about the person. Sometimes such thoughts can spiral to great lengths. When this happens all the flaws of that person are magnified in our eyes and we become blinded from their good, leading us to hate that person with great intensity. We start to see them as completely evil. No one is ever completely evil, even the most evil people in history often had a misconstrued rationale for their actions, that they saw as noble. Although this might seem very natural this is nothing other than the ploy of shaitan. We think these thoughts are our own because of what we have experienced but they’re not they are clear whisperings of the Shaytan that can have severe consequences. It’s precisely this type of thing that leads to a cycle of violence death and destruction that can continues for many years.
The proof of this being shaytan is the statement of Joseph after he reunited with his brothers.
Despite what his brothers did, he still blamed the satan
The other thing to remember regardless of how others are, we are only answerable for ourselves and our own actions so we need to conduct ourselves according to the examples of the Prophets and laws laid out in the Qur’an
O you who have believed, be persistently standing firm in justice, witnesses for Allah , even if it be against yourselves or parents and relatives. Whether one is rich or poor, Allah is more worthy of both. So follow not [personal] inclination, lest you not be just. And if you distort [your testimony] or refuse [to give it], then indeed Allah is ever, with what you do, Acquainted. (Quran 4:135)
I used this formula to achieve peace when I was troubled for many years by a large loss in a business partnership as result of not follow Islamic Guidlines in setting up the business in the first place. Negative feelings consume you and harm oneself more than the other. It’s better to forgive and wait for Allah’s promise of reward. Allah never goes back on His promise (Qur’an). It’s not going to be an easy journey but you’ve got to make it and it’s worth it. It took me over 3 years even though I am an Islamic Teacher, who is trying to constantly trying to lead by example to the people around me, my kids my wife and be a role model for the youth I teach , exposed to the Qur’an everyday. May Allah make it easy for you.