1 John 3:14-16 14 We know that we have passed from death unto life, because we love the brethren. He that loveth not his brother abideth in death. 15 Whosoever hateth his brother is a murderer: and ye know that no murderer hath eternal life abiding in Him. 16 Hereby perceive we the love of God, because He laid down his life for us: and we ought to lay down our lives for the brethren.
The Bible calls hatred murder. Sometimes people can hurt you so badly that you can be tormented by the thought of them, tormented when you hear their name, and tormented by the thought that they might get away with what they did to you. When people hurt us, we must know that nothing happens that God hasn’t permitted. The book of Job teaches us that it doesn’t mean God necessarily causes all things to happen to us, but it can’t happen unless He approves it.
Secondly, we must know that we have to forgive people. You can be so angry with people that it ends up causing you to develop hatred against them. To hate is to murder. Not only do you murder yourself by losing joy and losing hope, but most people end up sharing their hatred of someone with others thus murdering their influence with others. God has forgiven you for great things and now you must turn around and do it for others. Forgiveness means that you release them from what they did to you and from your desire to punish them for it. It doesn’t mean a rekindling of a relationship or friendship and doesn’t even mean fellowship with that person.
Vengeance is the Lord’s, not yours and when you forgive someone you are releasing them and any “punishment” for what they did back to God.