I recently have been greatly wronged, mistreated and oppressed by someone very close to me, and i was just wondering..how will allah punish them?

Sorry that you had to go through that. Here are some Quranic verses on oppression:

Do not ever think that God is unaware of what the wrongdoers (or oppressors) do. He only defers them until a Day when the sights stare. (Verse 14:42)

If those who did wrong (or committed oppression) owned everything on earth, and the like of it with it, they would redeem themselves with it from the terrible suffering on the Day of Resurrection. But there will appear to them from God what they never anticipated. (Verse 39:47)

Had every soul which had done wrong (or committed oppression) possessed everything on earth, it would offer it as a ransom. They will hide the remorse when they witness the suffering, and it will be judged between them equitably, and they will not be wronged. (Verse 10:54)

Whether God punishes the person depends on whether you will eventually forgive them or not, and whether they will seek forgiveness or not, and whether God has a certain plan for making something good come out of the wrong they have done you. We can never predict what God is going to do next, since we do not know His wisdom and His plans. Something bad that happens now may have the greatest benefit for us ten years down the road, and a person who wrongs us now may do us a great favor in the future out of their feeling of guilt. And if they never repent and you patiently wait for God’s judgment without doing any evil toward them in return, then God can give you a great reward in this life and the next for your patience.

I recommend that you read the Quran, it has many verses that clarify these matters. In the story of Prophet Yusuf, his brothers oppress him by throwing him in a well and causing him to be sold into slavery. But God rescues him and makes him greatly superior to those who oppressed them. He is oppressed again by the elite women of his society who unjustly cause him to be thrown into prison, but God causes this to become a cause for him to be promoted into a very high position in the government. God is in charge of this world and He is capable of turning any oppression we suffer into something good for us down the road.