When someone brings you harm and makes you suffer, and everyday you are suffering because of that someone, what does Islam say about revenge, and is it true what goes around comes around, will that person suffer later in life or on day of judgement as a result of what they did to you?
As you are aware, Islam is the religion of forgiveness and it is emphasized as a positive act. So, Allah introduces himself as a merciful God. (e.g. as the Verse below)
إِنَّ اللَّهَ كانَ عَفُوًّا غَفُوراً
(Nisa 43) / نساء، 43.
Or for instance Allah orders or suggests the forgiveness.
خُذِ الْعَفْوَ وَ أْمُرْ بِالْعُرْفِ وَ أَعْرِضْ عَنِ الْجاهِلين
(al-A'raf 199) / الاعراف، 199
Of course it is necessary to point out that it does mean that always you do at. For instance if you want to forgive someone, thus it will make him more cheek or more cruel, so it will be harmful …, So it the mentioned case you ought not to be silent and Islam allows us to be like themselves.
فَمَنِ اعْتَدى عَلَيْكُمْ فَاعْتَدُوا عَلَيْهِ بِمِثْلِ مَا اعْتَدى عَلَيْكُم
Al-Baqarah 194 / البقره 194
Note: according to the verse above, we ought not to do something more than his oppression.
Anyhow, we ought not to forget that Allah is the best revenger, and according to Islam: as far as possible, strive not to be as revenger people (except some situations).
For further information, you can refer to the source below.